The only caveat is that AES is not necessarily a black box. It's possible there may be hidden structure to take advantage of, but if there is there's no reason to suspect it's one that's amenable to a quantum speedup.
As far as the Grover speedup goes, it's already optimal. Requiring O(sqrt(N)) queries is the proven lower bound for unstructured search.
As far as the Grover speedup goes, it's already optimal. Requiring O(sqrt(N)) queries is the proven lower bound for unstructured search.