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 (
    2348, 1659, 2082, 2325, 1721, 1973, 2337, 
    1705, 1660, 1748, 2080, 2083, 2092, 
    2084, 2093, 2086, 2085, 2088, 2087, 
    2089, 1912, 1768, 1712, 2327, 1803, 
    1789, 2026, 1904, 1946, 1905, 2090, 
    1937, 1995, 2097, 2096, 2095, 2094, 
    1900, 1988, 1945, 1942, 1941, 1998, 
    1899, 2016, 2025, 2081, 1787, 1983, 
    1959, 1984
  )

Query time 0.00075

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "53.56"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 51,
          "rows_produced_per_join": 51,
          "filtered": "100.00",
          "index_condition": "(`gaseus`.`pfv`.`variant_id` in (2348,1659,2082,2325,1721,1973,2337,1705,1660,1748,2080,2083,2092,2084,2093,2086,2085,2088,2087,2089,1912,1768,1712,2327,1803,1789,2026,1904,1946,1905,2090,1937,1995,2097,2096,2095,2094,1900,1988,1945,1942,1941,1998,1899,2016,2025,2081,1787,1983,1959,1984))",
          "cost_info": {
            "read_cost": "30.61",
            "eval_cost": "5.10",
            "prefix_cost": "35.71",
            "data_read_per_join": "58K"
          },
          "used_columns": [
            "variant_id",
            "position"
          ]
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "gaseus.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 51,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "12.75",
            "eval_cost": "5.10",
            "prefix_cost": "53.56",
            "data_read_per_join": "158K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}