MariaDB 10.3

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select version();

version()

10.3.36-MariaDB-1:10.3.36+maria~deb10-log

CREATE TABLE orders_copy (merchant_order_collection tinyint, order_list JSON);

INSERT INTO orders_copy 
VALUES 
(0,'{\\"order\\":[{\\"product_id\\":3,\\"quantity\\":5,\\"product_name\\":\\"Ikan salmon bakar\\"}]}');
SELECT JSON_EXTRACT(order_list, '$.order[*].product_id') 
FROM orders_copy WHERE id = 3; 

Unknown column 'id' in 'where clause'

SELECT JSON_EXTRACT(order_list, '$.order[*].product_id') 
FROM orders_copy; 

JSON_EXTRACT(order_list, '$.order[*].product_id')

null

SELECT *
FROM orders_copy; 

merchant_order_collection
order_list

0
7b5c226f726465725c223a5b7b5c2270726f647563745f69645c223a332c5c227175616e746974795c223a352c5c2270726f647563745f6e616d655c223a5c22496b616e2073616c6d6f6e2062616b61725c227d5d7d

SELECT JSON_EXTRACT(od, '$.order[*].product_id') 
FROM 
(SELECT *, REPLACE(order_list,'\\','') AS od FROM orders_copy) A; 

JSON_EXTRACT(od, '$.order[*].product_id')

[3]