SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e831995a6a5a33275edde4fe1138dd80b73faf8404c81c516c1abd0c29e3473' 
  AND token = 'nGp6kaPiOYTxsAO0KcqsQ5K2fzPVhkf8HcBG9DRl1Gk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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