SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a4f991da909b2864cb7c843af196d96ad350fa52608b425797a99254f958136' 
  AND token = 'OrdeS7TuAR05cZizOZUVidoJpE+lU6b10oUCdFdrK+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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