SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f81c5ec8ed3985f00f441eb0c826d5c76594c086136bbd4b9cd38701ec3f48b' 
  AND token = 'hRnsBsfRa52aePCrqPfXub8eTZLcDKYRgR8tCjA5zQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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