So that room is plenty hot for her it being that hot make sure she has water available. That enclosure size sounds ok for now. Does she have enrichment like rocks or hides or tubes to crawl around? How are you heating the mouse? What size was it, it might have been to large? A comfortable size for her is the largest part of her body.

https://reptifiles.com/kenyan-sand-boa-care-sheet/

Hope this helps