SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '308bae5ac31440a84d409c796767b809289253f2f2401005dd79127eca48d02b' 
  AND token = 'MTaxKv8t++z0JzAKG17ns7ZVHBN4DJjQ+IO9E8TzvLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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