in the slow log, a table is queried according to the index and 0 items of data are returned. Millis shows that it takes more than 200ms, but the executionTimeMillisEstimate of each execution phase is 0.
imitates this query record to query in shell, and the exlpain execution plan shows that it takes 0 Ms.
so why does it take so long in the slow log when no data is found at all?

{
    "op" : "query",
    "ns" : "xxx",
    "command" : {
        "find" : "xxx",
        "filter" : {
            "type" : {
                "$exists" : false
            },
            "id" : "198006886"
        },
        "sort" : {
            "_id" : -1
        },
        "projection" : {
            "mmm" : 1,
            "_id" : 0
        },
        "$readPreference" : {
            "mode" : "secondaryPreferred"
        },
        "$db" : "xxx"
    },
    "keysExamined" : 0,
    "docsExamined" : 0,
    "hasSortStage" : true,
    "cursorExhausted" : true,
    "numYield" : 0,
    "locks" : {
        "Global" : {
            "acquireCount" : {
                "r" : NumberLong(2)
            },
            "acquireWaitCount" : {
                "r" : NumberLong(1)
            },
            "timeAcquiringMicros" : {
                "r" : NumberLong(219017)
            }
        },
        "Database" : {
            "acquireCount" : {
                "r" : NumberLong(1)
            }
        },
        "Collection" : {
            "acquireCount" : {
                "r" : NumberLong(1)
            }
        }
    },
    "nreturned" : 0,
    "responseLength" : 234,
    "protocol" : "op_query",
    "millis" : 252,
    "planSummary" : "IXSCAN { id: -1, mmm: -1 }",
    "execStats" : {
        "stage" : "CACHED_PLAN",
        "nReturned" : 0,
        "executionTimeMillisEstimate" : 0,
        "works" : 1,
        "advanced" : 0,
        "needTime" : 0,
        "needYield" : 0,
        "saveState" : 0,
        "restoreState" : 0,
        "isEOF" : 1,
        "invalidates" : 0,
        "inputStage" : {
            "stage" : "PROJECTION",
            "nReturned" : 0,
            "executionTimeMillisEstimate" : 0,
            "works" : 3,
            "advanced" : 0,
            "needTime" : 2,
            "needYield" : 0,
            "saveState" : 0,
            "restoreState" : 0,
            "isEOF" : 1,
            "invalidates" : 0,
            "transformBy" : {
                "id" : 1,
                "_id" : 0
            },
            "inputStage" : {
                "stage" : "SORT",
                "nReturned" : 0,
                "executionTimeMillisEstimate" : 0,
                ......