Unfortunately there are no keys - and a search will ultimately prove futile, too. Attempting brute force yields no results too, since the doors are apparently rather heavily reinforced - the Red Templars seemed to want to make sure that absolutely nobody would be able to get out of this place.

The well-furnished cell isn't going to win any awards for being comfortable any time soon, but it definitely looks a lot better than any of the other cells Ciri passed by and had been in, in one case. There's an actual bed set up at the end as well as a table at the corner, right next to the entrance of the cell itself. Near the ceiling is a tiny window that's somehow carved out, with bars across it. All in all its a nice cell - but still very much a cell all the same.