The Orange led by 12 points in the second half, but Maryland stormed back, drawing to within 56-55 with 47.7 seconds to go on steal and subsequent free throw by Jake Layman.
After Syracuse's C.J. Fair missed a jumper on the next possession, Keita blocked Nick Faust's potential go-ahead shot and Orange (26-2, 13-2, ACC) held on to break a two-game losing streak.
With the victory, Syracuse pulled within one game of Atlantic Coast Conference-leading Virginia. The Orange play at Virginia Saturday.
The Terrapins (15-13, 7-8) were paced by Seth Allen with 22 points.
Dez Wells provided 15 points and seven rebounds.
Millions of Getty images now available for free via embed tool
Boston schools pull out free condoms over wrapping complaints