SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f276c280195dba0eae5c29bab9b8acc9de5460a1800756246515e96b7719a52' 
  AND token = 'hwTsxzMcMjblVBtKRv1/ZtrT77YC59BRkZLKVd+FsMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}