SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99b141588103db4456ac51f9c9f27270690d9324b36da9c9759617384b1fc633' 
  AND token = 'hXRDhPZVYlGasEgR4ub3DBCk398+cCoHMTPz8oOW/MQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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