See these rows in the ColumnFamilyInputFormat.getSplits method :
assert jobKeyRange.start_key == null : "only start_token supported";
assert jobKeyRange.end_key == null : "only end_token supported";
So, the question is why start_key and end_key aren't supported ?
What I actually need is the ability to specify exact rowKey (UUID). Not a key range.
I believe I can do this with same start and end keys but not with tokes.