SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4937a7b568a0310ca61e94f8377c06309901019adace9771628b52ad161be1e4' 
  AND token = 'kCLTnwItH33zESG7iumEE9XNpw9hhDiB3RmqXsXCHbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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