SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31700cd2f01b62458974461b670c8619bd5117e9907e401901763f7b504ba365' 
  AND token = 'AtONRdbY/0e9f1RI1bEcY9GKaapAi/WeaVTc4DOZT0E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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