The key fit in the key hole. (pt. tense)
The key fitted in the key hole. (pt. tense)
Wow! I had to go to the dictionary to make sure the otherwise impeccable Bhai had not lost his mind.
In the US, I have never heard "fitted" for simple past. I was about to reply that as an irregular verb, "fit" took "fit" as the simple past and "fitted" only as the participle.
Live and learn!
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
I spent years teaching irregular verbs to French teenagers, the school course books give lists of verbs to be learnt/learned by rote (horrible system). In the irregular verb lists they sometimes (not always) give the AmE version for information, while stressing that the BrE versions are to be used in all school work. So, the verb "to fit" is shown as regular in BrE and irregular in AmE. There are of course more verbs that are irregular in BrE and regular in AmE.
In the US the usual past tense is 'fit', whereas in British English it is regular.