I urge all of you to check your key number, if it starts with 5000 (Yamaha) you have a unique key. That being said, if someone knowledgeable wants to steal your cart it would only take about a minute to replace the switch.

If a thief wants your cart, they will get it. No key is required.
Have theft insurance.

Back in the day I owned a '69 Camaro which I planned on restoring. Didn't have a garage at the time and my neighborhood was well...so I smeared heavy grease all over the body and removed the steering wheel. Couldn't afford theft insurance and it wasn't stolen but it there was evidence it was tried. Laughed my ass off thinking how grossed out the potential thieves got !

Senseable approach
 

This makes sense to me unless you have an older cart that is not worth much.