Hey, sorry to be boring, but i don’t really think you code are secure and also optimized.
Whenever the user tries to lock or unlock his own car, it will check on server-side in the database, with a query. If someone does much of them, the server can probably crash as a spam.
Did you try to check it as one-time check or even when user takes his own car out of the garage?
Take a look at some resources, do some open source function or config event for user customize.
Some opinions and options you can take. I just the callback everytime it’s not OK.