SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79d9bd5a55b6a8e561bc0c75df7996929dfdbda9d4d101a7f4d71384465ecfe0' 
  AND token = 'JSxqaQv6jjtTiKytNqPU4EbUmv+htlhpNysnT7Sqsqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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