SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7603f04fdf2873fa8883155536e1a1dd253404972d8fbe0fc3d358da724d94b' 
  AND token = '2vVhMhh2PKLU4DyPYNZrZo3ACzTT8XBb8+uhpiThy1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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