Sorry I forgot about the table description.
The table is pretty simple There are about 15 fields and about 75 million records. This query is supposed to use three fields to narrow down the records. One is a timestamp column, the other is a macaddress type, the third is a integer. All three are indexed.
The query seems to first use the timestamp column which results in a huge number of records and then filters out using the integer and the macaddr indices. If it was to use the integer index first it would start with a tiny number of records.