diff --git a/src/langbot/pkg/api/http/service/apikey.py b/src/langbot/pkg/api/http/service/apikey.py
index c46b5608..5e6ff15d 100644
--- a/src/langbot/pkg/api/http/service/apikey.py
+++ b/src/langbot/pkg/api/http/service/apikey.py
@@ -52,6 +52,9 @@ class ApiKeyService:
 
     async def verify_api_key(self, key: str) -> bool:
         """Verify if an API key is valid"""
+        if not isinstance(key, str) or not key.startswith('lbk_'):
+            return False
+
         result = await self.ap.persistence_mgr.execute_async(
             sqlalchemy.select(apikey.ApiKey).where(apikey.ApiKey.key == key)
         )
diff --git a/tests/unit_tests/api/test_apikey_service.py b/tests/unit_tests/api/test_apikey_service.py
new file mode 100644
index 00000000..67b6737b
--- /dev/null
+++ b/tests/unit_tests/api/test_apikey_service.py
@@ -0,0 +1,40 @@
+from __future__ import annotations
+
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, Mock
+
+import pytest
+
+from langbot.pkg.api.http.service.apikey import ApiKeyService
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize('api_key', [None, 123, b'lbk_bytes', '', 'plain_key', ' LBK_bad', 'sk-lbk_fake'])
+async def test_verify_api_key_rejects_non_lbk_keys_without_db_query(api_key):
+    persistence_mgr = SimpleNamespace(execute_async=AsyncMock())
+    service = ApiKeyService(SimpleNamespace(persistence_mgr=persistence_mgr))
+
+    result = await service.verify_api_key(api_key)
+
+    assert result is False
+    persistence_mgr.execute_async.assert_not_awaited()
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    ('db_row', 'expected'),
+    [
+        (object(), True),
+        (None, False),
+    ],
+)
+async def test_verify_api_key_keeps_db_validation_for_lbk_keys(db_row, expected):
+    query_result = Mock()
+    query_result.first.return_value = db_row
+    persistence_mgr = SimpleNamespace(execute_async=AsyncMock(return_value=query_result))
+    service = ApiKeyService(SimpleNamespace(persistence_mgr=persistence_mgr))
+
+    result = await service.verify_api_key('lbk_valid_format')
+
+    assert result is expected
+    persistence_mgr.execute_async.assert_awaited_once()