SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38c41052ba09148c05aa8bce48ce1f9c058dc43fa14b321071a6edc6e952ebe8' 
  AND token = 'PU/hAKoxBzjkZYRnc1UyZmaWGiVOy8CuikBgLeuTTTg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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