You purchased the wrong iPhone. Sprint iPhones are CDMA & require being first activated on Sprint's network, in the US, & once a customer, then requesting the sim slot be unlocked. Since you're not a customer, you won't be able to do that.
You might as well sell the phone & purchase one you can use where you live.
As has been stated, the only ones that can unlock your phone are Sprint themselves and if you are not a customer, then they won't do it, so the chances are that the OP has not unlocked his iPhone.
As has also been stated previously, you bought the wrong phone and should have bought a phone that would work in Russia, such as an iPhone from a European country and NOT the US.
For Sprint to unlock your phone, you need to be a customer of their and if you are not then they won't do it, so you have ended up with a useless phone that you now can't use.