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 (
    2906, 5879, 5523, 6689, 5876, 2908, 5474, 
    5452, 5405, 5404, 5527, 6686, 5494, 
    5593, 5488, 5403, 5492, 5453, 5491, 
    5446, 5536, 5551, 6688, 5553, 5515, 
    5435, 2909, 5454, 5558, 5792, 5449, 
    5556, 5519, 5601, 8723, 5444, 5490, 
    5429, 5497, 5483, 6208, 5530, 5531, 
    5769, 5528, 5537, 5557, 5586, 5430, 
    5448, 5587, 6690, 5790, 5436, 5522, 
    5598, 5517, 5451, 5478, 5442, 5510, 
    5552, 5509, 5535, 6242, 5437, 5485, 
    5479, 5518, 5441, 5434, 5590, 5493, 
    5526, 5484, 6219, 5402, 5482, 5589, 
    5600
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00201

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "56.65"
    },
    "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": 80,
      "rows_produced_per_join": 80,
      "filtered": "100.00",
      "index_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`product_id` in (2906,5879,5523,6689,5876,2908,5474,5452,5405,5404,5527,6686,5494,5593,5488,5403,5492,5453,5491,5446,5536,5551,6688,5553,5515,5435,2909,5454,5558,5792,5449,5556,5519,5601,8723,5444,5490,5429,5497,5483,6208,5530,5531,5769,5528,5537,5557,5586,5430,5448,5587,6690,5790,5436,5522,5598,5517,5451,5478,5442,5510,5552,5509,5535,6242,5437,5485,5479,5518,5441,5434,5590,5493,5526,5484,6219,5402,5482,5589,5600)) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "48.65",
        "eval_cost": "8.00",
        "prefix_cost": "56.65",
        "data_read_per_join": "365K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}