Does a real "megapixel lens" exist?
This is a misnomer, if not pure marketing corruption of terms. The lens doesn't do anything to the "megapixel count", that's determined solely by the sensor.
At most the lens might have the capability to resolve details to a level where a sensor of at least a certain element density is required to record them, but then you'd still not have a number of pixels as the size of the sensor as well as its element density determines that.