Inefficient use of index scan on 2nd column of composite index during concurrent activity

Hi team

Second column of composite index not in use effectively with index scan
when using second column at where clause

I have composite index on (placedon,id) of test
When quering select * from test where id = '4234';
Value of id changes and during concurrent activity and cpu utilization
increased toomuch that i have observed which means query plan changed why

I could see index scan with explain for it

Is there any way to keep index scan for it during even on concurrency
rather than seperate index on second column of composite index ?

Hope everyone understand this

Regards,
Durga Mahesh