SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc92806c8e797de8bf7acc72299445ba259f731410ba41230556034fe72db49f' 
  AND token = '7K2AxmXHRemUKlekD8s6AYfNn9iYy9lbpjGRVgDqDO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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