SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6aa8997a4b652b49851cc6b90ad25f50bd210444bff7e5b2ff8c44e78c88d53' 
  AND token = 'FV+t+ZHQU+XUQxOKVvAYgXLjcd9LAEPIi80hY2YOSsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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