Absent info on how your query relates to `tbl` DDL, I guessed what a,b,c,d in your query represent, populated `tbl` with a hundred rows of random data, and obtained this result ...
EXPLAIN
SELECT id as a, CAST(t_p_type AS signed) AS b, t_p_key as c, created_at as d
FROM tbl
WHERE dipped_at IS NULL AND t_p_key='12345'
ORDER BY a LIMIT 18446744073709551610 OFFSET 0\G
id: 1
select_type: SIMPLE
table: tbl
partitions: NULL
type: ref
possible_keys: third_party_key
key: third_party_key
key_len: 1031
ref: const,const
rows: 1
filtered: 100.00
Extra: Using index condition
If that's wrong, please show the query with its actual columns.
Edited 4 time(s). Last edit at 09/23/2021 11:59AM by Peter Brawley.