SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7731f7ba331a94450371121824e388449f5b66e2cb814f74c559873ae71a8e0' 
  AND token = 'YrPteURtE8wz9PZXmlYaSsGx1Ts5N9/qBuLBtwtbj5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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