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.
Anywhere Door, Small Light, Take-copter (briefly).
If we assume you are referring to the (Japanese original order) and the episode commonly labeled as Episode 44 of Season 17 in international listings, here is a plausible piece — a fictional yet realistic plot summary for such an episode, written in the style of the show: Title: The Anywhere Door's Lost Key (どこでもドアの鍵なくしちゃった)
Nobita is excited for a summer trip to a tropical island using Doraemon's Anywhere Door. However, in his haste, he accidentally drops the door's special key — a small, golden, magnetic device — into a sewer grate while running away from Gian, who wants him to join a grueling baseball practice.
Desperate, Nobita uses the Small Light to shrink himself and search the sewer. Inside, he encounters a lost baby crow who has swallowed the key, thinking it was a shiny pebble. Nobita befriends the crow, but Gian and Suneo — also shrunk — chase him, thinking Nobita is faking the crisis to avoid practice.