DME operates 24 hours with no curfew, so transfer facilities should be available. Further information on http://domodedovo.ru/en/main/transfer/info/.

I believe the plane you are arriving with is the same on you'll leave on. In case there would be immigration issues they'd likely put you back on the same plane ... I would just check with LX beforehand to see if they have any issues to let you board the flight to DME without a Russian visa.