SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0d6fb09badd819d5a8b97740392fa5ff47f45934ed51839925eb47e69e55644' 
  AND token = 'cb8M/6miAYMf8wYUktVbsXaWTlkvm0+Rk+zrnvHdCOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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