SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description, 
  cscart_product_descriptions.meta_keywords, 
  cscart_product_descriptions.meta_description, 
  cscart_product_descriptions.search_words, 
  cscart_product_descriptions.promo_text 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    31135, 40732, 40733, 40537, 40538, 40539, 
    38833, 32125, 38832, 38830, 38831, 
    39074, 38180, 38181, 38794, 31134, 
    31136, 31139, 31140, 31141, 31144, 
    31145, 31153, 31155
  ) 
  AND cscart_product_descriptions.lang_code = 'fr'

Query time 0.00975

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "57.61"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 24,
      "rows_produced_per_join": 24,
      "filtered": "100.00",
      "index_condition": "((`ea201_diorama`.`cscart_product_descriptions`.`product_id` in (31135,40732,40733,40537,40538,40539,38833,32125,38832,38830,38831,39074,38180,38181,38794,31134,31136,31139,31140,31141,31144,31145,31153,31155)) and (`ea201_diorama`.`cscart_product_descriptions`.`lang_code` = 'fr'))",
      "cost_info": {
        "read_cost": "52.81",
        "eval_cost": "4.80",
        "prefix_cost": "57.61",
        "data_read_per_join": "91K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "meta_keywords",
        "meta_description",
        "search_words",
        "promo_text"
      ]
    }
  }
}