SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '643243abcf07084187b467677ef120bbee9ee920ffdf01058007f0a3a080e50f' 
  AND token = 'sABAJRehWCbIq6LCDWgDQBYmyC/nwjVJTbpN+zAJrx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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