Easy option. Sitting in the car. Lock and unlock the doors several times. In some systems this will reset the kill switch system.
More surefire way- Disconnect the battery, re-connect. Try it.
After that, if no success, you have a hard kill switch. You need to find what it is, it could be anything, but it most certainly some sort of electronic control on your dash that you need to push while turning the ignition. At this point, I would pull the car manual, read it, and call a local Lexus dealer.