Low-profile clear cover for a basement window
Do a search for shutter caps.  These are metal caps that go over the tops of shutters.  They will help with the top, but not likely the splash-back from the ground.  If you can find a roofer or a siding contractor with a sheet metal brake (and is willing to deal with a small project) you could easily bend a strip of metal, perhaps 3 or 4 inches wide, to create a narrow shed roof/awning over the window to direct the water away.  You can lap it under the siding if you have siding or adhesive and caulk if you have brick.  You might even find a suitable piece of "L" flashing, valley flashing or drip edge that might work at the local building supply or lumber yard.