SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b5a0ac619bbcfe0b67905a8a625eb5873a2493afa5688e7788217a260145bdb' 
  AND token = 'pIYNs/ouA0IvREdzkYCdCCfIMqpWhOusSGArq4XtVJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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