InnoDB: Is a covering index in the form of (PK, col1, col2, col3) redundant?
PRIMARY index in InnoDB is a tree where the primary key field (property) is a key and remaining columns are the value. In a secondary index the key are the index fields and the value is a primary key. In your case the secondary index has fields (property, value, and property). (property, value) is a key and property is a value.
The secondary index is larger and redundant, so MySQL make a right decision to use the PRIMARY index.

Check out a presentation I gave on InnoDB indexes structure for more details.
https://www.slideshare.net/akuzminsky/efficient-indexes-in-mysql