SELECT 
  cscart_sd_labels_custom.*, 
  cscart_sd_labels_custom_descriptions.* 
FROM 
  cscart_sd_labels_custom 
  LEFT JOIN cscart_sd_labels_custom_descriptions ON cscart_sd_labels_custom_descriptions.label_code = cscart_sd_labels_custom.label_code 
  AND cscart_sd_labels_custom_descriptions.lang_code = 'de' 
WHERE 
  1 
  AND cscart_sd_labels_custom.used = 'Y' 
ORDER BY 
  cscart_sd_labels_custom_descriptions.name asc

Query time 0.00037

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_sd_labels_custom ALL 10 Using where; Using temporary; Using filesort
1 SIMPLE cscart_sd_labels_custom_descriptions eq_ref PRIMARY PRIMARY 56 mahm3t_cs443.cscart_sd_labels_custom.label_code,const 1 Using where

Result

label_code background_color text_color used filter_key name lang_code
label2 #0b5394 #ffffff Y V 3-fach-Verglasung de
label3 #0b5394 #ffd966 Y U 4-fach-Verglasung de
label10 #8e7cc3 #ffffff Y G Dauerlüftung de
label7 #cc0000 #ffffff Y X Elektro de
label9 #6aa84f #ffffff Y K Klappfunktion de
label1 #000000 #ffffff Y Z Kunststoff de
label5 #ff0000 #ffffff Y W Neue Rezieptur de
label8 #cc0000 #ffd966 Y J Solar de
label4 #351c75 #ffffff Y T VSG innen de
label6 #6d9eeb #ffffff Y Q Weiß de