SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3574df92f503c2180d7692f6b359833175f8c8889c6444d568e0745a41232f9a' 
  AND token = 'M9CNBvQSdGNfLXwlZjZlBzNGMI8FkZtZnm6nhgX2Igw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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