Just considering the keys, you can use ismember (though I'm not sure why there's a limitation that cells must be cell arrays of character vectors, and can't be numbers..)
[mask] = ismember(cell2mat(B.keys),cell2mat(A.keys))
cnt = sum(mask)
[mask] = ismember(B.keys,A.keys)
If you need to check if values are the same, you can iterate through the matched keys and use isequal()
