I put my bike lock keys and house key on a ring with a multitool (Leatherman or Gerber, not a bike multitool). The Leatherman has proven to be a jersey pocket eater so I made a custom leather bag for it and the keys. For longer rides, the Leatherman plus keys go in my left jersey pocket. For intown and commutes, the Gerber. The Gerber is smaller,lighter and faster to grab for a quick lock-up. The Leatherman is a real tool.

Ben