SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00b30f6d4c105a1460ce26f6be8973dd1f576cb680dc016949490898e1b47567' 
  AND token = 'qGxUos3YI5x6oQMudTmscPq9ZH91v/AUlCmlTejaE80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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