The music needs to be about 2 minutes at most, and no less than 30 seconds. No action, or anything, just ambient sci-fi music.
for music try CCmixter, e.g.
http://dig.ccmixter.org/dig?dig-query=electronica [ check the license is compatible with your usage ]
e.g. http://ccmixter.org/files/gurdonark/29153 [ Attribution Noncommercial (3.0) ]
enter "sci fi" in the search, then sort by duration: