SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c39bcbae8f7a066c2be5b58e46fd49de64ddec1628a7ea1dd3182c6457c2802d' 
  AND token = '1jTkED5uienHErlZu7EaXUKlIm4PgQtJhsUHwXTX3ms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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