Not with wifi, no. You'd probably be best off picking up an RF keyfob and matching receiver from somewhere; adafruit has a few, can probably find a bunch on eba

Not with wifi, no. You'd probably be best off picking up an RF keyfob and matching receiver from somewhere; adafruit has a few, can probably find a bunch on ebay as well. The problem with Wifi is that because of everything involved down the chain, you can either have a really long battery life, or a really short bootup delay. For instant, with decent battery life, you're going to need a much simpler protocol.