SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6919b88997853d0525e753f29412304b7a01051601b7782cd7f5767b4275d533' 
  AND token = 'csGN+lOXtb0F8LpqWRD4s5+pslstRjnzW7qCZn6VKgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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