SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '356b84c6c5df00dfb2ec6aaf4de831829454577fe5bddd4591914ea592fdd900' 
  AND token = '8bRWSFrcLBabVQMe4hDd1moPpHjFUYjVc7morDEvXc0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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