SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6718b76c6d7afa1b7c85f48d039390a57ea46140c82bde8d006cedc70b6e1f4f' 
  AND token = '7kG2YeO0nIEphHQK5ngwFb+OwnfhrjyQbqLQ396N6XU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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