SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cf50b41c903697c1cc28f47a8203ccc9d37b75fbcc301c71406864ccccefdb4' 
  AND token = 'X+JzL7jxVepPH1IovE0rUeyuDGIb8rRDkugsN8iyRik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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