On Python 3 you can use the itertools islice to slice the dict.items() iterator
import itertools
d = {1: 2, 3: 4, 5: 6}
dict(itertools.islice(d.items(), 2))
{1: 2, 3: 4}
Note: this solution does not take into account specific keys. It slices by internal ordering of d, which in Python 3.7+ is guaranteed to be insertion-ordered.