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 (428031) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00052

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
428031 <p></p><p>Proiectata pentru uz zilnic<br />- Functia TARE, pentru a scadea ambalajul produsului cantarit.<br />- Perfect pentru a masura cantitatile de ingrediente, in bucatarie <br />- Design unic<br />- Display LCD usor de citit<br />- Poate cantari pana la 5Kg<br />- Se inchide automat cand nu este utilizat o perioada de timp<br />- Ideal pentru a cantari unt, faina, ceai, condimente, etc.<br />- Greutate produs: aprox. 325g<br />- Greutate minima: 1 gram<br />- Unitati: g / lb / oz<br />- Greutate maxima: 5000g<br />- Volumul bolului de cantarire: 1l<br />- Functioneaza cu 2 baterii 1.5V AA (not incluse)<br />- Material:ABS Plastic  <br />- Dimensiuni: 160x210x120<br />- Pachetul include:<br />  1 x cantar plastic<br />  1 x bol transparent plastic</p>