What do you call a row of keys (music)?

Solution 1:

An organ has one or more manuals (and, usually, a pedalboard which the organist plays with his feet).

manual noun

3 an organ keyboard played with the hands not the feet.

[ODO]

The collection of manuals, together with the stops, is called the console. However, one would normally say "the organ has four manuals" rather than "the organ console has four manuals", because the manuals are always in the console.

Solution 2:

An organ console has one or more keyboards (if you mean to be played with the hands or feet) or one or more manuals (if you are referring only to keyboards played by the hands).

http://en.wikipedia.org/wiki/Organ_console