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.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (2379, 8354) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00064

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1.42"
    },
    "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": 2,
      "rows_produced_per_join": 2,
      "filtered": "100.00",
      "index_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`product_id` in (2379,8354)) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "1.23",
        "eval_cost": "0.20",
        "prefix_cost": "1.43",
        "data_read_per_join": "9K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}

Result

product_id short_description full_description unit_name
2379 <p>D<i>ouble A</i>&nbsp;Premium is a medium-high-grammage paper designed for printing premium professional documents such as reports or presentations. To achieve the very best render for this type of document, printers need premium-grade paper with the right weight and composition. Our product strikes the right balance, making it an excellent choice for high-standard printing.</p>
8354 <p>SkyLine Peel N Seal Manila Envelopes offer a secure and convenient way to store or send documents. Made from durable, high-quality paper, these envelopes are designed to protect your papers from bending or damage. The peel-and-seal closure makes sealing quick, clean, and adhesive-free&mdash;perfect for office, school, or home use. Each pack includes 50 sturdy envelopes, ideal for professional correspondence and everyday organization.</p> <p> </p>