I don't have map coordinates per say because it does not show up on Google Maps, but its just a half hour before reaching Chillam Choki on the Astore Deosai Road, and you can't miss it.
There are two hotels side by side on your left as you make a small turn on the road with the river running on your right hand side. Its the only two restaurants there. Now this was last year and maybe another small hotel is added to this location.
In any case, you can always ask people as you ride by where Chashma Hotel is, the locals know it very well and its right on the rout.