Here is the schedule from the official Aeroexpress website. In case you don't read Russian, the left column is time of departure from Moscow-Savelovskij Station; the right column is time of departure from Sheremetievo-2. Journey time is stated as 30 minutes in either case; ticket cost is 250 RUR.

Note that if you miss a x:55 train from Moscow-Savelovskij (or there is a service interruption) the train to Lobnya, as described in the original post of this thread, leaves 5 minutes later (it will take an extra 15-30 minutes since you'll have to connect to a bus or taxi, but could be a lifesaver).