mysql> alter table tbl_rf add index (macadd);
Query OK, 1691759 rows affected (1 min 42.98 sec)
Records: 1691759  Duplicates: 0  Warnings: 0

mysql>

mysql> select hex(forward_mer) from tbl_rf where macadd='001b.d712.5872' and date='2008-02-18-h22-m25-s09' and forward_mer is not null;
+------------------+
| hex(forward_mer) |
+------------------+
| NULL             |
+------------------+
1 row in set (0.06 sec)

mysql>