I have a real estate application and a "house" contains the following information:

house:
- house_id 
- address
- city 
- state
- zip
- price
- sqft
- bedrooms
- bathrooms
- geo_latitude
- geo_longitude

I need to perform an EXTREMELY fast (low latency) retrieval of all homes within a geo-coordinate box.

Something like the SQL below (if I were to use a database):

SELECT * from houses 
WHERE latitude IS BETWEEN xxx AND yyy
AND longitude IS BETWEEN www AND zzz

Question: What would be the quickest way for me to store this information so that I can perform the fastest retrieval of data based on latitude & longitude? (e.g. database, NoSQL, memcache, etc)?