SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '335f57221df9e42e48758e0458747090242b777a4b782d9113f70fe9181abaec' 
  AND token = 'M7fxyVKuZ3VWQjVThbiJqCt2t1dDU6k2tsuUDbqtZHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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