SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '584112c3798b760facb3af93dd6c5e3fd9719a685b75cc4d2d834e0c49f63a75' 
  AND token = '2r/+wUcqYJCxhLK7JlxsCKFbPmMmTmXrV04Qepn3yAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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