Indexation benefits on unlisted equity shares

I have purchased 90000 shares at 10/share of rs. 9 lacs in 2006 of a pvt ltd co., now i am selling them in 2021 at 43/share as per price determined by merchant banker.
my question is whether indexation benefit available in my case or not?
STT is not paid on these shares, does it affect the indexation benefit?