SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6fc749fbfc2939aeeed0bb94b34611748ebf6cc0ddccb76ab447be1e76cc59f' 
  AND token = '1Ca3kZwrJUdZIWEMDiVuOd1czxeK/atuQ67sbScEaRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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