Mongo DB query between dates is taking too long for last 10 days but not for more than 10

Question

Below query is giving results with in time frame ::

db.getCollection('XXX').find({'id':'YY', 'date' : { 
        $lt: new Date(), 
        $gte: new Date(new Date().setDate(new Date().getDate()-15))
      } })

but when I run ::

db.getCollection('XXX').find({'id':'YY', 'date' : { 
        $lt: new Date(), 
        $gte: new Date(new Date().setDate(new Date().getDate()-10))
      } })

it is taking too much time. I am using robo 3t to fetch results.