SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'en' 
WHERE 
  pfv.variant_id IN (
    71492, 71490, 71493, 71491, 71496, 71497, 
    71508, 71509, 71516, 71515, 71517, 
    77913, 78136, 78135, 78137, 80653, 
    80654, 82362, 82363, 82364, 82365, 
    82366, 82367, 82383, 82384, 82385, 
    83173, 83174, 83175, 83176, 83961, 
    83960, 83954, 83955, 83956, 83957, 
    83958, 83959, 84325, 84326, 84327, 
    84328, 85463, 85464, 85465, 85466, 
    85695, 85696, 85968, 85969, 85970, 
    85971, 85972, 86218, 86219, 86220, 
    86410, 86411, 86413, 86412
  )

Query time 0.00934

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 60,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (71492,71490,71493,71491,71496,71497,71508,71509,71516,71515,71517,77913,78136,78135,78137,80653,80654,82362,82363,82364,82365,82366,82367,82383,82384,82385,83173,83174,83175,83176,83961,83960,83954,83955,83956,83957,83958,83959,84325,84326,84327,84328,85463,85464,85465,85466,85695,85696,85968,85969,85970,85971,85972,86218,86219,86220,86410,86411,86413,86412)"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": ["dev_db.pfv.variant_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "pfvd.lang_code = 'en'"
        }
      }
    ]
  }
}