No, the GO:KEYS 3 IN does not come with a music rest. The dedicated music rest, MRGKS3/5, is sold separately. Please place your order at an authorized dealer near you.
NOTE: The music rests for the GO:KEYS 3 IN and those for GO:KEYS (1st gen.) are not mutually compatible. Please see the related article: GO:KEYS 3 IN: Do the music rests for GO:KEYS 5, GO:KEYS 3, or GO:KEYS 3 IN and for GO:KEYS (1st gen.) have mutual compatibility?