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 = 'vi' 
WHERE 
  pfv.variant_id IN (
    70876, 70877, 71009, 71008, 71007, 71010, 
    71100, 71099, 71098, 71097, 71096, 
    71095, 71094, 71101, 71547, 71551, 
    73505, 73504, 73525, 73524, 73539, 
    73538, 73927, 73928, 74069, 74070, 
    74068, 74495, 74496, 74494, 75634, 
    75632, 75633, 75649, 75650, 75651, 
    76716, 76717, 77294, 77296, 77295, 
    77297, 77299, 77298, 81485, 81486, 
    81487, 81488, 81489, 81490, 82368, 
    82369, 82370, 82371, 84291, 84292, 
    84293, 84766, 84430, 84431, 84432, 
    84433
  )

Query time 0.03030

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 (70876,70877,71009,71008,71007,71010,71100,71099,71098,71097,71096,71095,71094,71101,71547,71551,73505,73504,73525,73524,73539,73538,73927,73928,74069,74070,74068,74495,74496,74494,75634,75632,75633,75649,75650,75651,76716,76717,77294,77296,77295,77297,77299,77298,81485,81486,81487,81488,81489,81490,82368,82369,82370,82371,84291,84292,84293,84766,84430,84431,84432,84433)"
        }
      },
      {
        "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 = 'vi'"
        }
      }
    ]
  }
}