SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76298af8fe56d7282448afa04b874e7dd0b26758113ac85c9ac78e28840264c0' 
  AND token = 'NT29WThTpmIcAWhgg8zqSdoryGviXMbLqNTAOluy0ZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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