Temporary table creation takes long time RDS Server - memory

Question

Below query takes long time to create temporary table, its only have "228000" distinct record.
DECLARE todate,fromdate DATETIME;
SET fromdate=DATE_SUB(UTC_TIMESTAMP(),INTERVAL 2 DAY);
SET todate=DATE_ADD(UTC_TIMESTAMP(),INTERVAL 14 DAY);
SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;
DROP TEMPORARY TABLE IF EXISTS tempabc;
SET max_heap_table_size = 1024*1024*1024;
CREATE TEMPORARY TABLE IF NOT EXISTS tempabc
-- (index using BTREE(id))
ENGINE=MEMORY
AS
(
SELECT SQL_NO_CACHE DISTINCT id
FROM abc
WHERE StartTime BETWEEN fromdate AND todate
);
I already created index on 'startTime' coulmn, still it tooks 20 sec to create table. Kindly help me out to reduce the creation time.
More Info:-
I changed my query earlier I was using "tempabc" temporary table to get my output, now I am using IN clause instead of temporary table and now it is taking 12 sec to execute, but still more than expected time..
Earlier(taking 20-30 sec)
DECLARE todate,fromdate DATETIME;
SET fromdate=DATE_SUB(UTC_TIMESTAMP(),INTERVAL 2 DAY);
SET todate=DATE_ADD(UTC_TIMESTAMP(),INTERVAL 14 DAY);
SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;
DROP TEMPORARY TABLE IF EXISTS tempabc;
SET max_heap_table_size = 1024*1024*1024;
CREATE TEMPORARY TABLE IF NOT EXISTS tempabc
-- (index using BTREE(id))
ENGINE=MEMORY
AS
(
SELECT SQL_NO_CACHE DISTINCT id
FROM abc
WHERE StartTime BETWEEN fromdate AND todate
);
SELECT DISTINCT p.xyzID
FROM tempabc s
JOIN xyz_tab p ON p.xyzID=s.ID AND IFNULL(IsGeneric,0)=0;
Now(taking 12-14 sec)
DECLARE todate,fromdate Timestamp;
SET fromdate=DATE_SUB(UTC_TIMESTAMP(),INTERVAL 2 DAY);
SET todate=DATE_ADD(UTC_TIMESTAMP(),INTERVAL 14 DAY);
SELECT p.xyzID FROM xyz_tab p
WHERE id IN (
SELECT DISTINCT id FROM abc
WHERE StartTime BETWEEN fromdate AND todate )
AND IFNULL(IsGeneric,0)=0 GROUP BY p.xyxID;
But we need to achieve 3-5 sec of execution time.
This is my explain output.
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: abc
partitions: NULL
type: index
possible_keys: ix_starttime_id,IDX_Start_time,IX_id_starttime,IX_id_starttime_prgsvcid
key: IX_id_starttime
key_len: 163
ref: NULL
rows: 18779876
filtered: 1.27
Extra: Using where; Using index; Using temporary; Using filesort; LooseScan
*************************** 2. row ***************************
id: 1
select_type: SIMPLE
table: p
partitions: NULL
type: eq_ref
possible_keys: PRIMARY,IX_seriesid
key: PRIMARY
key_len: 152
ref: onconnectdb.abc.ID
rows: 1
filtered: 100.00
Extra: Using where
Explain in JSON format
EXPLAIN: {
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "10139148.44"
},
"grouping_operation": {
"using_temporary_table": true,
"using_filesort": true,
"cost_info": {
"sort_cost": "1.00"
},
"nested_loop": [
{
"table": {
"table_name": "abc",
"access_type": "index",
"possible_keys": [
"ix_starttime_tmsid",
"IDX_Start_time",
"IX_id_starttime",
"IX_id_starttime_prgsvcid"
],
"key": "IX_id_starttime",
"used_key_parts": [
"ID",
"StartTime",
"EndTime"
],
"key_length": "163",
"rows_examined_per_scan": 19280092,
"rows_produced_per_join": 264059,
"filtered": "1.37",
"using_index": true,
"loosescan": true,
"cost_info": {
"read_cost": "393472.45",
"eval_cost": "52812.00",
"prefix_cost": "446284.45",
"data_read_per_join": "2G"
},
"used_columns": [
"ID",
"StartTime"
],
"attached_condition": "(`onconnectdb`.`abc`.`StartTime` between <cache>(fromdate#1) and <cache>(todate#0))"
}
},
{
"table": {
"table_name": "p",
"access_type": "eq_ref",
"possible_keys": [
"PRIMARY",
"IX_seriesid"
],
"key": "PRIMARY",
"used_key_parts": [
"ID"
],
"key_length": "152",
"ref": [
"onconnectdb.abc.ID"
],
"rows_examined_per_scan": 1,
"rows_produced_per_join": 1,
"filtered": "100.00",
"cost_info": {
"read_cost": "9640051.00",
"eval_cost": "0.20",
"prefix_cost": "10139147.44",
"data_read_per_join": "2K"
},
"used_columns": [
"ID",
"xyzID",
"IsGeneric"
],
"attached_condition": "(ifnull(`onconnectdb`.`p`.`IsGeneric`,0) = 0)"
}
}
]
}
}
}
Please suggest.