SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8308c86292664dfebdac7e37af48e241542a3175300d4070aef9cc8d1381a033' 
  AND token = 'HzFEyDix6iYDoN4OUWTggWjgV+XXLvWnhMQRXPf8Au8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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