The optimization process and recommendations:

1. Avoid Calling Functions With Indexed Columns (query line: 29): When a function is used directly on an indexed column, the database's optimizer won’t be able to use the index. For example, if the column `sysdate` is indexed, the index won’t be used as it’s wrapped with the function `to_char`. If you can’t find an alternative condition that won’t use a function call, a possible solution is to store the required value in a new indexed column.
2. Avoid Calling Functions With Indexed Columns (query line: 30): When a function is used directly on an indexed column, the database's optimizer won’t be able to use the index. For example, if the column `sysdate` is indexed, the index won’t be used as it’s wrapped with the function `to_char`. If you can’t find an alternative condition that won’t use a function call, a possible solution is to store the required value in a new indexed column.
3. Use Numeric Column Types For Numeric Values (query line: 15): Referencing a numeric value (e.g. 100) as a string in a WHERE clause might result in poor performance. Possible impacts of storing numbers as varchars: more space will be used, you won't be able to perform arithmetic operations, the data won't be self-validated, aggregation functions like SUM won't work, the output may sort incorrectly and more. If the column is numeric, remove the quotes from the constant value, to make sure a numeric comparison is done.
4. Use Numeric Column Types For Numeric Values (query line: 17): Referencing a numeric value (e.g. 6802) as a string in a WHERE clause might result in poor performance. Possible impacts of storing numbers as varchars: more space will be used, you won't be able to perform arithmetic operations, the data won't be self-validated, aggregation functions like SUM won't work, the output may sort incorrectly and more. If the column is numeric, remove the quotes from the constant value, to make sure a numeric comparison is done.
5. Use Numeric Column Types For Numeric Values (query line: 23): Referencing a numeric value (e.g. 1) as a string in a WHERE clause might result in poor performance. Possible impacts of storing numbers as varchars: more space will be used, you won't be able to perform arithmetic operations, the data won't be self-validated, aggregation functions like SUM won't work, the output may sort incorrectly and more. If the column is numeric, remove the quotes from the constant value, to make sure a numeric comparison is done.
6. Use Numeric Column Types For Numeric Values (query line: 31): Referencing a numeric value (e.g. 3) as a string in a WHERE clause might result in poor performance. Possible impacts of storing numbers as varchars: more space will be used, you won't be able to perform arithmetic operations, the data won't be self-validated, aggregation functions like SUM won't work, the output may sort incorrectly and more. If the column is numeric, remove the quotes from the constant value, to make sure a numeric comparison is done.

The optimized query:

SELECT
        DISTINCT kb.FSSBD,
        kb.SSSBD,
        ca.AUFNR,
        ca.PLNBEZ,
        kt.maktx,
        ca.GAMNG,
        ca.GMEIN 
    FROM
        SAPR3.CRHD cr,
        SAPR3.KBED kb,
        SAPR3.CAUFV ca,
        SAPR3.MAKT kt 
    WHERE
        cr.MANDT = '100' 
        AND cr.OBJTY = 'A' 
        AND cr.WERKS = '6802' 
        AND cr.STAND = 'MPL06' 
        AND cr.LVORM = ' ' 
        AND cr.MANDT = kb.MANDT 
        AND cr.KAPID = kb.KAPID 
        AND kb.TYPKZ IN (
            '1', '7'
        ) 
        AND kb.PLNUM = ' ' 
        AND kb.MANDT = ca.MANDT 
        AND kb.BEDID = ca.BEDID 
        AND ca.LOEKZ = ' ' 
        AND kb.FSTAD <= to_char(sysdate + 10, 'YYYYMMDD') 
        AND kb.SENDD >= to_char(sysdate - 10, 'YYYYMMDD') 
        AND kb.BSTKZ = '3' 
        AND kt.mandt = ca.mandt 
        AND kt.matnr = ca.PLNBEZ 
        AND kt.SPRAS = 'E' 
    ORDER BY
        kb.FSSBD