This works perfect!!
SELECT
BILLCHARGE_ID,
EXT_ATTR,
json_extract(replace(replace(replace(EXT_ATTR, '{', '["'), '}', '"]'), ',', '","'), '$[9]') AS EXPRESION
FROM BILL_CHARGE WHERE BILLCHARGE_ID=751000000157777658
BILLCHARGE_ID EXT_ATTR EXPRESION
751000000157777658 {,,,,,,,,,(19)22595418,100230,,1} (11)24598458
Thank you all!!