SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4a842b892bcbe119e94615b2dc9c6c1c6d338ebd20ea40377099b9f01e53ee5' 
  AND token = 'plXqFcWMo5YX/IFQvouWZK6M/JDVgNtYvup1VmnBwM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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