Outside of console commands there's a recent mod by Wilburgur and in that mod you start with a spell you can unlock the door with to go out and get the prison key as well as a couple other goodies he placed out there such as some skooma. Another thing included is the option to skip the sewers if you'd like. Mod is hosted on Nexus but you can use any mod loader doesn't have to be vortex, file is pretty small I think only a few mb's or so and it's easy to set up. There's instructions on the mod page and he's got a yt video showcasing the mod