I was able to obtain the first part of the key from Sandomo on a level 8, I would therefore assume it is possible to enter at level 8 if you were to assemble the complete key.
However, I did not have the assistance to run to the Oramond key on a level 8 to test the assembly and actually enter the spawn. I also tested trying to give pieces obtained on a higher level character to the level 8 to assemble the key without walking to oramond/folda, which was not successful. It appears you obtain a quest flag required to assemble the key upon picking up the other two pieces.