SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e66b5496bcf5a58c095dd1e64a8f8e47709c16d83ce3a40f2785c0c3fdb3ab0d' 
  AND token = 'SaJRYKTkYbnGN1tyXY0NGEGSAU8E1pEofkq7wVwpTXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}