diff --git a/src/aiida/storage/sqlite_zip/orm.py b/src/aiida/storage/sqlite_zip/orm.py
index ad0412f006..0f51c12534 100644
--- a/src/aiida/storage/sqlite_zip/orm.py
+++ b/src/aiida/storage/sqlite_zip/orm.py
@@ -17,7 +17,7 @@
 from functools import singledispatch
 from typing import Any, List, Optional, Tuple, Union
 
-from sqlalchemy import JSON, case, func
+from sqlalchemy import JSON, case, func, select
 from sqlalchemy.orm.util import AliasedClass
 from sqlalchemy.sql import ColumnElement
 
@@ -289,7 +289,11 @@ def _cast_json_type(comparator: JSON.Comparator, value: Any) -> Tuple[ColumnElem
             raise NotImplementedError('The operator `contains` is not implemented for SQLite-based storage plugins.')
 
         if operator == 'has_key':
-            raise NotImplementedError('The operator `has_key` is not implemented for SQLite-based storage plugins.')
+            return (
+                select(database_entity)
+                .where(func.json_each(database_entity).table_valued('key', joins_implicitly=True).c.key == value)
+                .exists()
+            )
 
         if operator == 'in':
             type_filter, casted_entity = _cast_json_type(database_entity, value[0])
diff --git a/tests/cmdline/commands/test_calcjob.py b/tests/cmdline/commands/test_calcjob.py
index a9ca84a991..c3f45f195e 100644
--- a/tests/cmdline/commands/test_calcjob.py
+++ b/tests/cmdline/commands/test_calcjob.py
@@ -241,9 +241,6 @@ def test_calcjob_outputcat(self):
         retrieved.base.repository._repository.put_object_from_filelike(io.BytesIO(b'5\n'), 'aiida.out')
         retrieved.base.repository._update_repository_metadata()
 
-    # This currently fails with sqlite backend since the filtering relies on the `has_key` filter which is not
-    # implemented in SQLite, see https://github.com/aiidateam/aiida-core/pull/6497
-    @pytest.mark.requires_psql
     def test_calcjob_cleanworkdir_basic(self):
         """Test verdi calcjob cleanworkdir"""
         # Specifying no filtering options and no explicit calcjobs should exit with non-zero status
@@ -269,7 +266,6 @@ def test_calcjob_cleanworkdir_basic(self):
         result = self.cli_runner.invoke(command.calcjob_cleanworkdir, options)
         assert result.exception is not None, result.output
 
-    @pytest.mark.requires_psql
     def test_calcjob_cleanworkdir_advanced(self):
         # Check applying both p and o filters
         for flag_p in ['-p', '--past-days']:
diff --git a/tests/orm/test_querybuilder.py b/tests/orm/test_querybuilder.py
index 862474bc76..e39f20a7b9 100644
--- a/tests/orm/test_querybuilder.py
+++ b/tests/orm/test_querybuilder.py
@@ -1537,7 +1537,6 @@ def test_iterall_with_store_group(self):
         for pk, pk_clone in zip(pks, [e[1] for e in sorted(pks_clone)]):
             assert orm.load_node(pk) == orm.load_node(pk_clone)
 
-    @pytest.mark.requires_psql
     @pytest.mark.usefixtures('aiida_profile_clean')
     def test_iterall_persistence(self, manager):
         """Test that mutations made during ``QueryBuilder.iterall`` context are automatically committed and persisted.
diff --git a/tests/storage/sqlite/test_orm.py b/tests/storage/sqlite/test_orm.py
index 21c75f1302..0d859d6bac 100644
--- a/tests/storage/sqlite/test_orm.py
+++ b/tests/storage/sqlite/test_orm.py
@@ -24,7 +24,7 @@
         ({'attributes.float': {'of_type': 'number'}}, 1),
         ({'attributes.true': {'of_type': 'boolean'}}, 1),
         ({'attributes.false': {'of_type': 'boolean'}}, 1),
-        ({'attributes.null': {'of_type': 'null'}}, 2),
+        ({'attributes.null': {'of_type': 'null'}}, 3),
         ({'attributes.list': {'of_type': 'array'}}, 1),
         ({'attributes.dict': {'of_type': 'object'}}, 1),
         # equality match
@@ -35,7 +35,7 @@
         ({'attributes.false': {'==': False}}, 1),
         ({'attributes.list': {'==': [1, 2]}}, 1),
         ({'attributes.list2': {'==': ['a', 'b']}}, 1),
-        ({'attributes.dict': {'==': {'key1': 1, 'key2': None}}}, 1),
+        ({'attributes.dict': {'==': {'key-1': 1, 'key-none': None}}}, 1),
         # equality non-match
         ({'attributes.text': {'==': 'lmn'}}, 0),
         ({'attributes.integer': {'==': 2}}, 0),
@@ -89,9 +89,11 @@
         ({'attributes.integer': {'in': [5, 6, 7]}}, 0),
         ({'attributes.integer': {'in': [1, 2, 3]}}, 1),
         # object operators
-        # Reenable when ``has_key`` operator is implemented, see https://github.com/aiidateam/aiida-core/issues/6498
-        # ({'attributes.dict': {'has_key': 'k'}}, 0),
-        # ({'attributes.dict': {'has_key': 'key1'}}, 1),
+        ({'attributes.dict': {'has_key': 'non-exist'}}, 0),
+        ({'attributes.dict': {'!has_key': 'non-exist'}}, 3),
+        ({'attributes.dict': {'has_key': 'key-1'}}, 1),
+        ({'attributes.dict': {'has_key': 'key-none'}}, 1),
+        ({'attributes.dict': {'!has_key': 'key-none'}}, 2),
     ),
     ids=json.dumps,
 )
@@ -111,13 +113,17 @@ def test_qb_json_filters(filters, matches):
             'list': [1, 2],
             'list2': ['a', 'b'],
             'dict': {
-                'key1': 1,
-                'key2': None,
+                'key-1': 1,
+                'key-none': None,
             },
         },
         backend=backend,
     ).store()
     Dict({'text2': 'abcxXYZ'}, backend=backend).store()
+
+    # a false dict, added to test `has_key`'s behavior when key is not of json type
+    Dict({'dict': 0xFA15ED1C7}, backend=backend).store()
+
     qbuilder = QueryBuilder(backend=backend)
     qbuilder.append(Dict, filters=filters)
     assert qbuilder.count() == matches
diff --git a/tests/test_nodes.py b/tests/test_nodes.py
index bd971d37db..6f64ab6d2d 100644
--- a/tests/test_nodes.py
+++ b/tests/test_nodes.py
@@ -162,7 +162,6 @@ def init_profile(self, aiida_localhost):
         """Initialize the profile."""
         self.computer = aiida_localhost
 
-    @pytest.mark.requires_psql
     def test_with_subclasses(self):
         from aiida.plugins import DataFactory