Can connect to Elasicsearch but do not see any results. QueryInspector shows strange query

Hello this might be a grafana beginner question but I am really stuck here.

I have this elastic index

{
  "source_db_table1": {
    "aliases": {
      "fromkafka": {}
    },
    "mappings": {
      "properties": {
        "boolean_attr": {
          "type": "boolean"
        },
        "date_attr": {
          "type": "long"
        },
        "float_attr": {
          "type": "float"
        },
        "id": {
          "type": "long"
        },
        "int_attr": {
          "type": "long"
        },
        "msgtime": {
          "type": "long"
        },
        "str_attr": {
          "type": "text",
          "fields": {
            "keyword": {
              "type": "keyword",
              "ignore_above": 256
            }
          }
        }
      }
    },
    "settings": {
      "index": {
        "creation_date": "1595292501292",
        "number_of_shards": "1",
        "number_of_replicas": "1",
        "uuid": "O3reNKevS8OwfiwAPBgcpQ",
        "version": {
          "created": "7060199"
        },
        "provided_name": "source_db_table1"
      }
    }
  }
}

and have a (secured) Elastic connection which tests fine. The time field is the date_attr field.

When I try to query that index, nothing comes out of it. Neither under the original name nor under the alias. But I am getting a weird QueryInsepctor output that seems to grow over time:

Object

request:Object

url:"api/datasources/proxy/1/_msearch?max_concurrent_shard_requests=5"

method:"POST"

data:"{"search_type":"query_then_fetch","ignore_unavailable":true,
"index":"fro017pmf17pm","fro018pmf18pm","fro019pmf19pm",
"fro020pmf20pm","fro021pmf21pm","fro022pmf22pm","fro023pmf23pm"]} 
{"size":0,"query":{"bool":{"filter":[{"range":{"msgtime":  
{"gte":1595440770687,"lte":1595462370688,"format":"epoch_millis"}}},
{"query_string":{"analyze_wildcard":true,"query":"*"}}]}},"aggs":{"2":{"date_histogram": 
{"interval":"15s","field":"msgtime","min_doc_count":0,"extended_bounds":
{"min":1595440770687,"max":1595462370688},"format":"epoch_millis"},"aggs":{}}}} "

response:Object

took:1

responses:Array[1]

0:Object

Any ideas? What am I doing wrong?