Not using the windows key, but after looking into this myself (in windows 10) I am using the Caps Lock key as my own shortcut key.
Using AutoHotkey I have reassigned caps lock to mimic a control key, and then control and caps lock to actually use caps lock. This means when I hit capslock on it's own nothing happens. Auto hotkey script:
;capslock = ctrl key, ctrl and capslock = capslock
Now I have an abundance of combinations for shortcuts to use which are not used by other applications. Caps lock and ..... you choose. Unlimited options of what you want this to trigger, either use Auto Hotkey script or like I've done just trigger a .bat file.
Example that I use every morning when at work.
Capslock & A::
;log into network locations bat