The reason flights take a different amount of time, depending on the direction is prevailing winds, not the earths rotation. This is because the atmosphere rotates with the earth, and the plane has a constant airspeed traveling both ways. However due to the coriolis effect the prevailing winds have a constant eastwards or westwards direction (as explained in this wikipedia article), making the ground speed (airspeed + wind speed) different in both directions.
The effect the earth's daily rotation is on the weight of the airplane due to the centrifugal force (which exists in our frame of reference). This effect is very small and doesn't impact the speed of flight
Ok, back to Toronto-Moscow. As you can see in this map the flight path goes northwards over greenland and closer then normally to the north pole.
This means that the prevailing winds blow more perpendicularly (east or west) to the planes movements, thus having a smaller impact on the flight duration.
To test this theory I looked up flights between Moscow and Dubai, as they are almost perfectly north/south of each other. And the flight time difference is only 10 mins! Showing thats flights going north or south have a lower difference then those going east/west