On Python 3, use dct.keys() to get a dictionary view object, which lets you do set operations on just the keys:
>>> for sharedkey in dct1.keys() & dct2.keys(): # intersection of two dictionaries
... print(dct1[sharedkey], dct2[sharedkey])
In Python 2.7, you’d use dct.viewkeys() for that.
In Python 2, dct.keys() returns a list, a copy of the keys in the dictionary. This can be passed around an a separate object that can be manipulated in its own right, including removing elements without affecting the dictionary itself; however, you can create the same list with list(dct), which works in both Python 2 and 3.
You indeed don’t want any of these for iteration or membership testing; always use for key in dct and key in dct for those, respectively.