SQL query optimization customer never bought?

Question

SQL query optimization

Used material
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+ off docks

Here, for anyone with subqueries, I'm wondering how NOT EXISTS, COUNT + DISTINCT, IS NULL will work with this structure

FROM User U
         INNER JOIN `Order` O on O.customer_id = U.id
         INNER JOIN OrderItem OI on O.id = OI.order_id
         INNER JOIN Product P on OI.product_id = P.id
         INNER JOIN Store S on P.store_id = S.id

Here is the current working version without taking into account the resources above. Optimizing it.

SELECT U.name, U.id as customer_id
FROM User U
WHERE U.id NOT IN (SELECT O.customer_id
                          FROM Product P
                                   JOIN OrderItem I on P.id = I.product_id
                                   JOIN `Order` O on I.order_id = O.id
                          WHERE P.store_id = 5)

MariaDB RDBMS on which I tested the query.

Original dump
SQLFiddle