SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3e90e9fcf7f251dcc31341140a2b164a3d4906f7d8f53b520bc52b262616da6' 
  AND token = 'LwgtOWYimE6Q7ayx5qszUJvYHEVaGO7h9Dp7U+7BYRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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