SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.meta_keywords, 
  cscart_product_descriptions.meta_description, 
  cscart_product_descriptions.search_words, 
  cscart_product_descriptions.promo_text, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    12654, 12655, 12656, 12657, 12658, 12659, 
    12660, 12661, 12662, 12663, 12664, 
    12665, 12666, 12667, 12668, 12669, 
    12670, 12671, 12672, 12673, 12674, 
    12675, 12676, 12677, 12678, 12679, 
    12680, 12681, 12682, 12683
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00076

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "30.31"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "index_condition": "((`test2_gaseus`.`cscart_product_descriptions`.`product_id` in (12654,12655,12656,12657,12658,12659,12660,12661,12662,12663,12664,12665,12666,12667,12668,12669,12670,12671,12672,12673,12674,12675,12676,12677,12678,12679,12680,12681,12682,12683)) and (`test2_gaseus`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "27.31",
        "eval_cost": "3.00",
        "prefix_cost": "30.31",
        "data_read_per_join": "136K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "meta_keywords",
        "meta_description",
        "search_words",
        "promo_text",
        "unit_name"
      ]
    }
  }
}