criteria = {
  event_id: '5ea92da4a5522a080614d29f',
  label_ids: ['6048a3c4b3d10c003c14b22e'],
  event_campaign_optin: true,
  _id: {
    "$in": [
      '60377e2172fcdc005b32e9ff',
      '5efdaeafa62e5400233657a0',
      '5efca695f820c7144e46ffda',
      '5ee0cebdb28593001c8bfaf2',
      '5ed65cd396f090255d089b77'
    ]
  }
}
Guest.where(criteria).count => 5

ap Guest.where(criteria).explain['queryPlanner'].except('rejectedPlans')
explain result :
{
    "plannerVersion" => 1,
         "namespace" => "mobicheckin-app.guests",
    "indexFilterSet" => false,
       "parsedQuery" => {
        "$and" => [
            [0] {
                "deleted_at" => {
                    "$eq" => nil
                }
            },
            [1] {
                "event_campaign_optin" => {
                    "$eq" => true
                }
            },
            [2] {
                "event_id" => {
                    "$eq" => BSON::ObjectId('5ea92da4a5522a080614d29f')
                }
            },
            [3] {
                "label_ids" => {
                    "$eq" => [
                        [0] BSON::ObjectId('6048a3c4b3d10c003c14b22e')
                    ]
                }
            },
            [4] {
                "_id" => {
                    "$in" => [
                        [0] BSON::ObjectId('5ed65cd396f090255d089b77'),
                        [1] BSON::ObjectId('5ee0cebdb28593001c8bfaf2'),
                        [2] BSON::ObjectId('5efca695f820c7144e46ffda'),
                        [3] BSON::ObjectId('5efdaeafa62e5400233657a0'),
                        [4] BSON::ObjectId('60377e2172fcdc005b32e9ff')
                    ]
                }
            }
        ]
    },
       "winningPlan" => {
              "stage" => "SORT",
        "sortPattern" => {
            "created_at" => -1
        },
         "inputStage" => {
                 "stage" => "SORT_KEY_GENERATOR",
            "inputStage" => {
                     "stage" => "FETCH",
                    "filter" => {
                    "$and" => [
                        [0] {
                            "deleted_at" => {
                                "$eq" => nil
                            }
                        },
                        [1] {
                            "event_campaign_optin" => {
                                "$eq" => true
                            }
                        },
                        [2] {
                            "event_id" => {
                                "$eq" => BSON::ObjectId('5ea92da4a5522a080614d29f')
                            }
                        },
                        [3] {
                            "label_ids" => {
                                "$eq" => [
                                    [0] BSON::ObjectId('6048a3c4b3d10c003c14b22e')
                                ]
                            }
                        }
                    ]
                },
                "inputStage" => {
                            "stage" => "IXSCAN",
                       "keyPattern" => {
                        "_id" => 1
                    },
                        "indexName" => "_id_",
                       "isMultiKey" => false,
                    "multiKeyPaths" => {
                        "_id" => []
                    },
                         "isUnique" => true,
                         "isSparse" => false,
                        "isPartial" => false,
                     "indexVersion" => 2,
                        "direction" => "forward",
                      "indexBounds" => {
                        "_id" => [
                            [0] "[ObjectId('5ed65cd396f090255d089b77'), ObjectId('5ed65cd396f090255d089b77')]",
                            [1] "[ObjectId('5ee0cebdb28593001c8bfaf2'), ObjectId('5ee0cebdb28593001c8bfaf2')]",
                            [2] "[ObjectId('5efca695f820c7144e46ffda'), ObjectId('5efca695f820c7144e46ffda')]",
                            [3] "[ObjectId('5efdaeafa62e5400233657a0'), ObjectId('5efdaeafa62e5400233657a0')]",
                            [4] "[ObjectId('60377e2172fcdc005b32e9ff'), ObjectId('60377e2172fcdc005b32e9ff')]"
                        ]
                    }
                }
            }
        }
    }
}