SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb943d581335ae4ba1e29d97a290131033ecd7a9b98290526abba11eff840881' 
  AND token = 'YRZmHlBovr5GtmLWweTearVCj41rCv3fu7qOEU9L7a0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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