How can I check whether my Magic Keyboard is genuine?

I am trying to find out whether my Magic Keyboard which I bought from a private person not using it anymore is genuine. The Apple Coverage site is not providing me any details stating that the serial number I inserted is not correct. Is it normal that MK s/n is not findable on this site? I doubt that the keyboard would be fake as it even has a well-working touch ID as well and the MacBook finds it as an Apple Keyboard - however, I wanna be sure.

Thanks all