SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff15b5a5d5a6d5f9a466531e98845a641c6da590c4fcd779168741d53e4f9de9' 
  AND token = 'SdHifDOrKK/JSMQtLzOCE8oH+lQ+S4Neh2mLedhH+ZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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