SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8f5618bb9ee90541ba3fe95b35e25741a198a762714b12b859b173665c0918f' 
  AND token = 'lLJebrGagNKZyKTxQcvyGgfwo2ypkxmb0XGHCnF70ro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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