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, 1978, 1973, 2362, 
    1705, 1660, 1748, 2080, 2083, 2084, 
    1912, 2327, 1803, 2094, 2016, 1900, 
    2095, 2096, 2097, 1937, 1988, 1787, 
    1995, 1946, 1723, 1905, 1789, 1941, 
    2075, 2025, 1899, 1998, 1975, 1974, 
    1972, 1942, 1983, 1959, 1984, 1945, 
    1904, 2026
  )

Query time 0.00080

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "47.26"
    },
    "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": 45,
          "rows_produced_per_join": 45,
          "filtered": "100.00",
          "index_condition": "(`gaseus`.`pfv`.`variant_id` in (2348,1659,2082,2325,1978,1973,2362,1705,1660,1748,2080,2083,2084,1912,2327,1803,2094,2016,1900,2095,2096,2097,1937,1988,1787,1995,1946,1723,1905,1789,1941,2075,2025,1899,1998,1975,1974,1972,1942,1983,1959,1984,1945,1904,2026))",
          "cost_info": {
            "read_cost": "27.01",
            "eval_cost": "4.50",
            "prefix_cost": "31.51",
            "data_read_per_join": "51K"
          },
          "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": 45,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "11.25",
            "eval_cost": "4.50",
            "prefix_cost": "47.26",
            "data_read_per_join": "140K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}