SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42878b551056e2a5634acbd2e1583dd355e8dcd2c5d0d83687c087e35ab792a3' 
  AND token = 'mlu9930wQQo64PXd8b9TRr2Sk+IKO5i5P3IL32T6N04=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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