Mongdb slow query analysis, where is the problem?

  mongodb, question
{
 "op": "query",
 "ns": "fund_statistic.fund_minute_statistic_collection1588",
 "command": {
 "find": "fund_minute_statistic_collection1588",
 "filter": {
 "time": {
 "$gte": 1531868400,
 "$lt": 1531887084
 }
 },
 "$db": "fund_statistic",
 "$readPreference": {
 "mode": "primaryPreferred"
 },
 "lsid": {
 "id": UUID(
 "f0a2ea9e-f8a4-484f-86cc-d01d04ebea3e"
 )
 }
 },
 "cursorid": NumberLong(
 "119871802965176"
 ),
 "keysExamined": 101,
 "docsExamined": 101,
 "numYield": 1,
 "locks": {
 "Global": {
 "acquireCount": {
 "r": NumberLong(4)
 }
 },
 "Database": {
 "acquireCount": {
 "r": NumberLong(2)
 }
 },
 "Collection": {
 "acquireCount": {
 "r": NumberLong(2)
 }
 }
 },
 "nreturned": 101,
 "responseLength": 7185,
 "protocol": "op_msg",
 "millis": 8960,
 "planSummary": "IXSCAN { time: 1 }",
 "execStats": {
 "stage": "FETCH",
 "nReturned": 101,
 "executionTimeMillisEstimate": 119,
 "works": 101,
 "advanced": 101,
 "needTime": 0,
 "needYield": 0,
 "saveState": 2,
 "restoreState": 1,
 "isEOF": 0,
 "invalidates": 0,
 "docsExamined": 101,
 "alreadyHasObj": 0,
 "inputStage": {
 "stage": "IXSCAN",
 "nReturned": 101,
 "executionTimeMillisEstimate": 119,
 "works": 101,
 "advanced": 101,
 "needTime": 0,
 "needYield": 0,
 "saveState": 2,
 "restoreState": 1,
 "isEOF": 0,
 "invalidates": 0,
 "keyPattern": {
 "time": NumberLong(1)
 },
 "indexName": "time_1",
 "isMultiKey": false,
 "multiKeyPaths": {
 "time": []
 },
 "isUnique": false,
 "isSparse": false,
 "isPartial": false,
 "indexVersion": 2,
 "direction": "forward",
 "indexBounds": {
 "time": [
 "[1531868400, 1531887084)"
 ]
 },
 "keysExamined": 101,
 "seeks": 1,
 "dupsTested": 0,
 "dupsDropped": 0,
 "seenInvalidated": 0
 }
 },
 "ts": ISODate(
 "2018-07-18T04:11:33.487Z"
 ),
 "client": "192.168.10.81",
 "allUsers": [],
 "user": ""
 }

You may not have indexed the time field. Without indexing, the query is linear. It took a long time to traverse the entries in the database.
You can see that db.collection.getIndexes () can get your current cache list.
If not, and this business scenario is more commonly used, you can index the time field db.collection.createindex ({time: 1})