SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4603ab7f81a9ddb3cad63289ff08e2af301839934a6f5f64e8eef27439caecf' 
  AND token = 'QQhtUnnUhG8S3ngzSxDyNJhr01tWqFcOe829hPwKCLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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