window.location 设置当前窗口的网址。要打开新窗口，您需要使用 window.open 。这应该有效：

window.location sets the url of your current window. To open a new window, you need to use window.open. This should work:

function ToKey(){
    var key = document.tokey.key.value.toLowerCase();
    if (key == "smk") {
        window.open('http://www.smkproduction.eu5.org','_blank');
    } else {
        alert("Kodi nuk është valid!");
    }
}