SELECT 
  * 
FROM 
  cscart_product_options_exceptions 
WHERE 
  product_id = 6795 
ORDER BY 
  exception_id

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "cscart_product_options_exceptions.exception_id",
        "table": {
          "table_name": "cscart_product_options_exceptions",
          "access_type": "ref",
          "possible_keys": ["product"],
          "key": "product",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "ref": ["const"],
          "rows": 5,
          "filtered": 100,
          "attached_condition": "cscart_product_options_exceptions.product_id <=> 6795"
        }
      }
    }
  }
}

Result

exception_id product_id combination
542 6795 a:2:{i:1279;s:4:"4079";i:1280;s:4:"4082";}
543 6795 a:2:{i:1279;s:4:"4079";i:1280;s:4:"4084";}
544 6795 a:2:{i:1279;s:4:"4080";i:1280;s:4:"4081";}
545 6795 a:2:{i:1279;s:4:"4080";i:1280;s:4:"4083";}