SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15bd48904c506f72a69eb968d44aef0c78e316121e4e23ebfa70d3100444a383' 
  AND token = 'VX50ivJA7XIZw6PwNN1SyS1qiEcv0SRJMhvyvuRHD9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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