SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '393d77cf2cfa39d1fc6decb54c982e4bca4d73df49b8ce85d8c45f107bde58ed' 
  AND token = 'UxgQq7ldODqJGZjtjg58ZKF20DvUj+RS6LoNGHX/0Cc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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