SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '553c312ab8b2b323338da4d99c59508417b47822084a75b356f363f8a9d87ecd' 
  AND token = '7SY47PX/QhEn/ZL3tsfito+pOLj+xjWpYnl7yQiBDV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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