SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f74f9b9e9b83f5a7abaaeea36af91f74330d9d14a8d9009ddd70bdc3be0f4cf' 
  AND token = 'qemoJY8QbjuJ0XSBLzPUQsYTem6eMfyiwKhLEiU8Boc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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