Zabbix proxy item query

gistfile1.sql

mysql> explain select p.id,h.host,i.key_,p.clock,p.timestamp,
p.source,p.severity,p.value,p.logeventid 
from hosts h,items i,proxy_history p where h.hostid=i.hostid 
and i.itemid=p.itemid and p.id>21824754 order by p.id limit 1000\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: p
         type: range
possible_keys: PRIMARY,id
          key: PRIMARY
      key_len: 8
          ref: NULL
         rows: 1446768
        Extra: Using where; Using temporary; Using filesort
*************************** 2. row ***************************
           id: 1
  select_type: SIMPLE
        table: h
         type: index
possible_keys: PRIMARY
          key: hosts_1
      key_len: 66
          ref: NULL
         rows: 5
        Extra: Using index; Using join buffer
*************************** 3. row ***************************
           id: 1
  select_type: SIMPLE
        table: i
         type: eq_ref
possible_keys: PRIMARY,items_1
          key: PRIMARY
      key_len: 8
          ref: zabbix_proxy.p.itemid
         rows: 1
        Extra: Using where
3 rows in set (0.05 sec)