I understand. Unfortunately as far as I know there is not any way. Lets see if anyone else knows away, who knows.But I don't want to start my Surface if a key is beeing pressed...
He says that that does not work.That came from Windows Phone Central... they seem to think it works... IDK.
http://m.wpcentral.com/surface-pro-3-type-cover-disable-it-save-your-battery