Converting Integer timestamp to Date

Having a hard time converting timestamp in MYSQL saved as INTEGER data type and getting error: returned error 'Out of range value for column ‘created_at’ : value 4294967295 is not in class java.lang.Integer range

select TO_TIMESTAMP(created_at) from ch_activities limit 10;

Even Casting select to_timestamp(cast(created_at as varchar)) as dt from ch_activities limit 10 throws: returned error 'Out of range value for column ‘created_at’ : value 4294967295 is not in class java.lang.Integer range

But Somehow this works: select to_timestamp(dt) from (

select cast(created_at as varchar) as dt from ch_activities limit 10)

Please explain magical sorcery? Thanks