SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef2b2c6688a006f25ab7d21568eaac2f04f2a6e5de0039887145af5b913fe3f5' 
  AND token = 'LPu1HwiC+o4lVN9Lzcg5+iv8OHlGPZmFcWMJPkWphsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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