Yes, OUTENB does affect the LOCK output. OUTENB is a bit that disables the parallel data outputs when set high. It also disables the LOCK pin, which is then pulled high via internal pullups. The LFLTB pin is also affected and is pulled down when OUTENB = 1.
To detect if you are locked, it is recommended to read the LOCKED bit (B7) in register 0x04 rather than monitoring the LOCK pin. The LOCKED bit is unaffected by OUTENB.