SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4521437e6d7b15685b7de7696d489b66bd5fbe1c9c5d7d5bc43723bc3881b801' 
  AND token = 'QSGXKAWj1GFHaBkA3S63FvL7Z+HFlXjr8E7J+VASzps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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