SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd1f1869b8b2d6b4c0c5cffdfecf3307585651737c9d992deb0a37765c3b7357' 
  AND token = 'lkAwJzlMIsrhr6eHr1Qt1yBB8sKlRnJTEqPXVPsRzlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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