SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f1ffd6bbe884b09150f05c1fd321ae13cd78a05910e1dd2cdc3d6fbc32dfb7f' 
  AND token = 'gIakbPDI12zjacDIRadk+vzBZgSZ0ygiVJ4pp6Bwbho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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