SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ad7dffd1e1c255e62c6af90b139ce28eb21dae052563a566ef62dd6add601b5' 
  AND token = 'UeGFihO0H8QDDlaE6ewzSAleehmqeVw42t85DFGMrYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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