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 (
    21181, 21182, 21183, 21184, 21185, 21186, 
    21187, 21188, 21189, 21190, 21191, 
    21192, 21193, 21194, 21195, 21196
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00923

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id", "idx_product_lang"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 16,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (21181,21182,21183,21184,21185,21186,21187,21188,21189,21190,21191,21192,21193,21194,21195,21196) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
21181 nut-cap<p>Part number 863553E000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21182 Garnish assembly - fender side, left<p>Part number 87711T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21183 Garnish assembly - fender side, right<p>Part number 87712T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21184 Garnish assembly-front door side, left<p>Part number 87721T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21185 Garnish assembly - front door side right<p>Part number 87722T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21186 Garnish assembly - rear door side left<p>Part number 87731T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21187 Garnish assembly-rear door side, right<p>Part number 87732T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21188 Garnish assembly-cutter side, left<p>Part number 87741T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21189 Garnish assembly-cutter side, right<p>Part number 87742T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21190 Clip-side sill molding mounting<p>Part number 87767J9000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21191 Molding assembly - side sill, left<p>Part number 87751T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21192 Molding assembly - side sill, right<p>Part number 87752T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21193 Strip-side sill front molding, left<p>Part number 877E1T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21194 Strip-side sill front molding, right<p>Part number 877E2T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21195 Garnish assembly-fender lower, left<p>Part number 877H5T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21196 Garnish assembly-fender lower, right<p>Part number 877H6T6000UYH</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>