SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b8fbe8164120330f524cc3732a7bf0d5d9f869c15d3a253e4b075a81c69af3f' 
  AND token = 'y748295u+E9nA40AZcwONPV6LUIigXZZebXBc/ItEsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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