Why are young adult girls called ‘kutty’ and ‘koche’’ in colloquial Malayalam?

Things I overheard or read today…

Enthu rasaa aa kuttyye kaanaan (kutty was in her early 30s)

Kalyanam aay alle? Koche evidenna? (Koch was in her mid 20s)

Insta comment under a prank video… Aa kochinte tholi urinju poyi… (Koch looked like she was in her early 20s)