has got = present perfect tense
The present perfect is a present tense. It always tells us something about now.
eg. Sandy has lost her key.(present perfect)
This means that she doesn't have her key now.
Do not use the present perfect when you talk about a finished time. Use past tense.
has got = past perfect tense
Sometimes we talk about something that happened in the past:
eg. Sandy arrived at the party.
This is the starting point of the story. Then, if we want to talk about things that happened before this time, we use the past perfect(had..),
eg. Sandy arrived at the party, Ms Yu had already gone home.
buy an english grammar book if you want more details.