وعليكم السلام ورحمة الله وبركات
According to the consensus of the Muslim scholars, it is haram to keep three-dimensional figures of any animate beings.
The only exception is children's toys as it was narrated by 'Aisha (رضي الله عنها): “I used to play with dolls in the presence of the Prophet (ﷺ) and I had friends who would play with me. When the Messenger of Allaah (ﷺ) entered they would hide themselves and he would call them to come and play with me." [Sahih al-Bukhari 6130]
In conclusion, it is haram to keep such key chains.
جزاك الله خيرا