YA book in a prison or slum city with a boy who finds a key or crystal to teleport

[Luke Koning]

Looking for a book I read when a late teen young adult I want to say around 2010. I remember it was kind of steam punkish and it involved a kind of slum city where a boy finds either a key or crystal that allows him to teleport. And I believe the main antagonist watched from a clock tower kind of thing and I think it was a woman but not sure. Sorry for so few details and I know it's a long shot but I have been unable to find this book any other way.

[Nadine]

Could it be Incarceron by Catherine Fisher?

[Luke Koning]

Nadine wrote: "Could it be Incarceron by Catherine Fisher?"

It is not. Reading that is what reminded me of the book I'm trying to find. Thank you though!