A key change is nothing complicated, in fact it can be easier on guitar than non-stringed instruments. If you compare the two verse parts you see that the notes all change in the same way, all you do is lift the entire riff up one string. That's a Key Change.
The riff only stays in A briefly, then drops back to E before entering the chorus.
VERSE
E repeat
E [----------------------------------
B [----------------------------------
G [----------------------------------
D [-------------2-0-------4-----0--2-
A [-----------2---------2-----2------
E [-0-----3-4------------------------
KEY CHANGE then return to E
A
E [----------------------------------
B [----------------------------------
G [-------------2-0-------4-----0--2-
D [-----------2---------2-----2------
A [-0-----3-4------------------------
E [----------------------------------
