SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a40fd64840ac63e24375ce7fe576767b75f7ff9aeba8925c593683cd48ef18d3' 
  AND token = '1rBxuIkaThWEyRcUW8tg7gzBSZUoABTESBlPwekv/z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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