SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6786f134cf9eef8b65b370ecac2c8eed694baff67a03e738cea2e34ab8692504' 
  AND token = 'AVuu9WwO8vY949pAEaXBLq98xWx4QaGdRlmETthROhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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