SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fefb25050d3f846580b240f569160894f10ff4f53c48da34b12be4df99341ae8' 
  AND token = 'FeXQlrUokHvjub/iLhfDU2hVHDF62vxKLLxeBpxrHQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}