The third website also has a metasearch function which allows for last name and place name searches across all their affiliated databases. For a small location like Moltzahn, it is worthwhile to run a place name search without filling in the last name field, resulting in a list of all persons connected to that location. Unfortunately, in your case, neither Schwartz (or alternative spelling Schwarz) nor Klafehn are found in Moltzahn.
Best wishes for your genealogical endeavours from Germany!