SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a88b2fd6157b179e128646d0681e14471767174392addc1868c08c120004143b' 
  AND token = 'pPi9tPW1Bl2h6qtT0JMFVkL2+/vfeAhu+CckoVGL/uE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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