SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '554cd79d676cd0d6755894581535315cd042e98f53da824bae782ab994d8b195' 
  AND token = 'cAT3PZshK4qxJNzHgcflP6tHJBzaSvZ4wNgyuBEo/ac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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