Answer:
The comma should go after "electronic beats".
Step-by-step explanation:
MGMT’s music is infused with electronic beats, catchy lyrics and a pop-friendly sound.
If you'd like to go the extra step, you can use an oxford comma, which goes before the "and," and place it after "catchy lyrics".
MGMT’s music is infused with electronic beats, catchy lyrics, and a pop-friendly sound.
Both sentences are grammatically correct.