SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48d97aa88596680ac5a8c257b4282ff68b4fc5b96d8868cc98f896b478d3d315' 
  AND token = 'KI3Gz5QLJ7eIkUqALg3xUok4Ovr6krwI+yp7T8YLi68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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