SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a4b956e74d166497bf6584a6cc84e0cd41a39b2f1d7c464028efeff86c66952' 
  AND token = '1254dcrTY+UiGOokAQEY24vmYqWZQU3iu3xJ1FL+lgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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