SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d828cfdd21515c7d197078e1b268b86c71b6bad2308d3b6388b2afaa8b6830b' 
  AND token = 'kxfHp3qnTt2zt5rkoRMWtUa64ujxObxolx1oKVsYDj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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