SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f52a639c8c2ccf0b95334248841d5aa731360414830a422dc956a8bf68beeaa' 
  AND token = 'kAYeWYUTCc/usDsgVv3euksWIxybZOUNRy6dyZ+caG0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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