SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bf48b21a42346fd0428c6952545ba0eb5205d3e30cc65a577def24bee1e8e78' 
  AND token = 'JTMQrKSG7uWjumt5mepusZGALtltNbelvnxnffBYx2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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