SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3da8f92c94866463441e6703d9e43e60679d9cbe323abc89edc7bae784a8ef66' 
  AND token = 'KJAKtLqFmnU5Si+RBY/pBiiUSpfTsEBg4jfLhd/ecgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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