SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8b8801ad26ebfe0cfc163d576d54cdbf15040c5f59d8cbafe7c32d986ba8b21' 
  AND token = 'gvb3cAa2i0QXPVsInVKHHKlG/zV8Jqx/XoTmiJ3QYF4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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