It sounds like you're asking for the plot of Doraemon Season 17, Episode 44. However, please note that episode numbering varies significantly between different versions of the anime (e.g., 1979 series, 2005 series, and regional broadcasts like USA or India).
Anywhere Door, Small Light, Take-copter (briefly). doraemon season 17 episode 44
Without the key, the Anywhere Door is stuck on its last destination: the inside of Shizuka's bathroom (much to everyone's embarrassment). Doraemon panics, explaining that the spare key is at the 22nd-century repair shop, and delivery will take 24 hours. It sounds like you're asking for the plot
After a muddy chase through underground pipes, Nobita gets the crow to cough up the key by offering it a piece of candy from Doraemon's pocket. Gian, impressed by Nobita's determination, calls off practice. Without the key, the Anywhere Door is stuck
The group uses the Anywhere Door to go to the island — but Doraemon accidentally sets it to the North Pole. The episode ends with everyone shivering as a penguin waves at them.