SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd27f7627fd372787275ffaab62914ffab410f3957bab02292c1ef0c079e5b6dd' 
  AND token = '1qhRAQQRlbItfYyLwoy/V9GOHu4fDAjbgPsCnev+MsE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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