SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3908ce31a51d8b93455b8bb6623c22d0914765b5d834494ca9e5e1081a0798ef' 
  AND token = 'yIq63FVlqLcdmLf3YhpIb0GUYBeMWfRvAFfS2ZhTgHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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