There are some times when Salat is not good as between 5 P.M. and the sunset. What can I do if my Salat of Asr is not done until this time?

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

The preponderant opinion of Muslim scholars is that the prohibition of offering prayers after al-'Asr or during the other times in which the prayers are prohibited, applies only to the general voluntary prayers. Thus, offering the missed obligatory prayers or those voluntary prayers that have a reason is permissible.
Therefore, you are obliged to perform al-'Asr prayer during that time since the prohibition does not apply to the current obligatory prayer. There is no disagreement among scholars concerning this ruling.
Allah knows best.