SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf951269d105cf76c3799185681b3bbdcfd8bf03d2de8a514ffbb70187ae3ea6' 
  AND token = '7nn8ZxAbqXeJry6m94ohjHU+hnvDFENmfRNRv5mYnrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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