SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '723e1824b1d09f8f2ec6a464ee60850356f9232d604d60e4c6b7916ab8b374d4' 
  AND token = 'yMYjpAqBiUhzKVXLtE1yDC5k2+CHoj6uHKmlWIjz3ZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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