SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46f0356401ee371664f965ec719d98c4fed71aa458fcb4dfdf82925c8b9ab689' 
  AND token = '8Ab/6aFu+QKq+N9zDgtYyH78Qjc0dzuulb5WsHhhzVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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