SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6d4c908ffdfc87f2d29881d88ad2cf8b187887d56e017bd90f73c36be1494ad' 
  AND token = 'CJzPDrbYLg5yzwO26x55z7tt7zvtA9fhW/uMsXdxEnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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