SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39800b18b529aa494cab65e7f5f49b5ade3136bc267f95dea678e07957f822c4' 
  AND token = 'AYc4kd5a9KFPjyZLqMrLYroL2tzlRYQyu3G6OKBWOCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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