SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b595c3d669f16b6f5cac34788337ee396db01513e21463b4fae6fb5b9404635' 
  AND token = '5RJqzta46bq87gtR8vnU/ZAWCCrVBd5PcserbxZF3xo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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