SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6141875d7233520afee21769259eda367941afe96e7872cfdd249d9e036d088' 
  AND token = 'lpYUlz+scQR7BqSq1ma9TwcR65Dw59G9UWAhU3+bMsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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