I use an European online banking account with mobileTAN. The text message will be sent from Germany and is online valid for two minutes.
Will the message reach me in time in Far East Russia, roaming with German SIM card?
If you are asking how much time international sms's can take, I'd say about the same as local sms's (provided of course both sender and receiver have network coverage). I have used free sms providers on the internet who have their base/servers/providers in the US and messages to countries like Tunisia, India and Bangladesh have been almost instant.
It should be no problem at all. Of course it's possible, but very unlikely that the delivery takes more than 2 minutes.
Nowadays many people use messenger apps (like WhatsApp, Viber, Skype etc) than SMS so I think that if you have a good network coverage the delivery would take just a few seconds. If the phone has been out of coverage for a while, then it can take a while longer before the network makes its next attempt.