I've always put the key in the cup-holder for the service tech, made note of that for the service advisor, and that's where they will be when you get the car back.
If the key isn't there when you drop it off, prepare for a call or for your things to be rummaged-through.
If the key isn't there when you pick it up - don't leave until you get it back, or they remove or replace the wheel locks. Things become a lot more difficult / annoying if you leave without the key but the locks still on your car.
As mentioned above if you're using an OEM set the dealer should have a master key set on hand. That said we can't guarantee if the set remains complete. I had one case a few years ago where one wheel lock was hammered on so tight (with a flat tire) that the dealer would no longer try with their master key set because they were afraid of breaking it, as I had done with my key. They got the other 3 off though.
With a temporary plug I ended up at a wheel and tire shop where they removed the offending lock with some special tools / methods - I had to sign off accepting that my wheel or wheel stud may be damaged.
Since that faithful day I don't use them at all.
2018 Pacifica Hybrid - In Canada Eh!