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 (
    68347, 68346, 68345, 68344, 68343, 68348, 
    68352, 68351, 68350, 68349, 68353, 
    68596, 68595, 68594, 68593, 68592, 
    68597, 87019, 87020, 73300, 73301, 
    73481, 73480, 73689, 73688, 73957, 
    73956, 73955, 73954, 73958, 74498, 
    74499, 74497, 77945, 77943, 77944, 
    78278, 78277, 78280, 78622, 78621, 
    78651, 79176, 79177, 79178, 79182, 
    79183, 79184, 79185, 79186, 79187, 
    79232, 79233, 79234, 79632, 79633, 
    79634, 79635, 79644, 79645, 83984, 
    83985
  )

Query time 0.00481

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": 62,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68347,68346,68345,68344,68343,68348,68352,68351,68350,68349,68353,68596,68595,68594,68593,68592,68597,87019,87020,73300,73301,73481,73480,73689,73688,73957,73956,73955,73954,73958,74498,74499,74497,77945,77943,77944,78278,78277,78280,78622,78621,78651,79176,79177,79178,79182,79183,79184,79185,79186,79187,79232,79233,79234,79632,79633,79634,79635,79644,79645,83984,83985)"
        }
      },
      {
        "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'"
        }
      }
    ]
  }
}