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 (53, 52, 54) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00047

JSON explain

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      "key": "PRIMARY",
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      "key_length": "9",
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      "rows_produced_per_join": 3,
      "filtered": "100.00",
      "index_condition": "((`danishecarter_31jan`.`cscart_product_descriptions`.`product_id` in (53,52,54)) and (`danishecarter_31jan`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "6.61",
        "eval_cost": "0.60",
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        "data_read_per_join": "13K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}

Result

product_id short_description full_description unit_name
52 <p>1200W Peak Power<br /> 400W RMS Power<br /> 4 ohms Impedance<br /> 34Hz - 300Hz Frequency Response<br /> 6" Mounting Depth<br /> PP Cone with Diamond Array Pattern<br /> Dual-Ventilation System<br /> Rubber Surround</p>
53 <p>Super-sturdy, super powerful, the KFC-W3012 is a 12-inch, 4-ohm sub that handles an impressive 1200W of power. A truly high-performance sub, the KFC-W3012 has a long stroke design and a silver textured pattern cone woofer that adds strength and rigidity to the cone for maximum bass performance.</p>
54 <p>The TS-W3002D2/4 subwoofers are designed to produce enormously powerful music. Just take a look at its super-heavy-duty construction, all designed to handle up to 3,500 watts max. Double-stacked magnets for higher power, and a step-up radial surround for superior control and long excursions. We used a constructed cast-aluminum basket for this sub. Add in our patented IMPP cone and you've got a monster sub that can handle whatever you want to throw at it.</p>