SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd365d91e15d0673c608287f573736f53f673a7ddf3880bd7f28b3d704c90e4f4' 
  AND token = 'eyU4eRmhCQ/NMyFvnwBJ595T+kiyKwHFjiCiSKZpmlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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