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 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (415211) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1.00"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "const",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "ref": [
        "const",
        "const"
      ],
      "rows_examined_per_scan": 1,
      "rows_produced_per_join": 1,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "0.00",
        "eval_cost": "0.20",
        "prefix_cost": "0.00",
        "data_read_per_join": "6K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ]
    }
  }
}

Result

product_id short_description full_description
415211 <p>SIKS® jewelery scale with digital display 200 x 0.01, portable, black The weighing surface is made of stainless steel, it is smooth and flat, easy to clean.<br /></p> <p>The electronic scale has small dimensions and can be carried in a pocket, purse or bag without taking up much space.<br />LCD screen with blue lighting.<br />Easy to use.<br />Recommended for weighing jewelry, coins, medicine, food, etc<br />Siks digital scale</p> <p>Specifications:<br />- capacity / readability: 200g / 0.01g<br />- TARE function (cancellation of the weight already placed on the scale, only the weight of objects added later is displayed.)<br />- black colour;<br />- dimensions: 127 x 76 x 16 mm;<br />- weight: 155g;<br />- battery: 2 x AAA (not included);<br />- display: LCD screen;</p> <p>  Tips:<br />- place the scale on a flat and solid surface;<br />- do not put it in water.</p> <p></p>