You won't get a good picture with 64 pixels.
with the 40° version @2m distance you'll get a horizontal view of 1,46 mt, so about 9 squared centimeters per pixel
with the 60° version @2m distance you'll get a horizontal view of 2,31 mt, so about 14 squared centimeters per pixel
I'm not familiar with lenses for this type of sensors, so nothing I can say about this could help you... I just know that the mlx90620 works just fine without them. I don't know if particular lens exists and could help to narrow the FOV