find the previous owner and kick them in the junk for installing keyed lugnuts and not including the key
If the opening at the end of the lug nut is small enough you may be able to pound a 1/2 drive ratchet in it. But I would check with some places that sell this style lug and see if you can get a key.
There is a lugnut group buy going on right now if you decide to ditch these. Edit- looks like you will have to make a few more posts to get into that thread though