SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9596afa81640ea92966f25d641a351f00fb18d28f8ae078c80c111da86a15068' 
  AND token = 'Pn9aLkmnsOIwCTZDmb+jV62KGY9797VFoyGEWxGa0NE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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