In theory they should give you access as you have the same day int'l connection. I don't think SU does through check-in at outstations like CAI so you will have to get your boarding pass to LED at a transfer desk at SVO. That's when you should ask them for the lounge invite. The lounge is pretty basic but is a much more civilised place to kill an hour or so than anywhere in the international terminal.

P.S. You do know you'll need to get on a transfer bus to get to the domestic terminal, do you? It's on the opposite side of the runways from where you're arriving from CAI.