From MongoDB docs:

explain.executionStats.totalKeysExamined

Number of index entries scanned. totalKeysExamined corresponds to the nscanned field returned by cursor.explain() in earlier versions of MongoDB.

1. This are good news when you have totalKeysExamined > 0 , this mean your query is using index. Here it is important to understand what is the size of your database , index selectivity , frequency and use case of this query to be identified if 103,000 is a good examination number for your search.

2. If you have totalKeysExamined = 0 , and totalDocsExamined > 0 than you may need to create some indexes.

3. The best case is when you have totalDocsExamined = 0 and totalKeysExamined > 0 , this is the case when you have the so called "covered query" , this is the fastest case where you search and load only from the index in memory and do not touch the rest part of the documents from storage.