Concatenated Column not using Index

SQL Text   : select Department_id , Manager_id 

                from employees where First_name || ' - ' || last_name

                in ('Neena - Kochhar')

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| Id  | Operation                            | Name      | Rows  | Bytes | Cost (%CPU)| Time     |

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|   0 | SELECT STATEMENT  |                      |     1 |    22 |     3   (0)| 00:00:01 |

|*  1 |  TABLE ACCESS FULL| EMPLOYEES |     1 |    22 |     3   (0)| 00:00:01 |

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How can I make the above query use index, maybe I should try hints...