Hi,
correct me if I am wrong BUT
The first plan shows that the select statement returns 225K rows
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost |
-------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 225K| 26M| | 2357K|
The second one returns only 1 row
------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost |
------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 122 | 824K|

About your question, you cannot make a low cardinality column selective. You should use another column to apply a stronger predicate on it

Cheers