From documentation:
The $box operator specifies a rectangle for a geospatial $geoWithin query. The query returns documents that are within the bounds of the rectangle, according to their point-based location data. The $box operator returns documents based on grid coordinates and does not query for GeoJSON shapes.
If you insert this document...
db.Townships.insert(
{ "geometry" : [ -96.74084500000001, 36.99911500000002 ],
"type" : "Feature"
})
...your query will found it (but without index support).