is there any keyword like const or anything else which does the same job with it in lua?

I know this question is seven years old, but Lua 5.4
finally brings const to the developers!

local a <const> = 42
a = 100500

Will produce an error:

lua: tmp.lua:2: attempt to assign to const variable 'a'

Docs: https://www.lua.org/manual/5.4/manual.html#3.3.7.