Most of my SQL queries have `WHERE rec_id <> 'D';` as for example:

```
 select * from Table1 where Field1 = 'ABC' and rec_id <> 'D'

```

I added index on `REC_ID`. But when I run this query and look at the execution plan, the new index `(REC_ID)` is not used. The Execution plan shows Cost of 50% of nonClustered index `Field1` and `50% RID Lookup` (Heap) in `Table1`.

Why the index `REC_ID` not used?