[Answer]-Filtering two models

cars = Car.objects.distinct().filter(mileage__gte=500000) \
                             .exclude(visit__date__gte=time_threshold)

For your real models code should look like this:

samochody = Samochod.objects.distinct().filter(przebieg__gte=500000) \
                                       .exclude(wizyta__data__gte=time_threshold)