SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cd809cbc7f6969afdfccb253ce6f368865892b6f7acd1836a556bd272e09a51' 
  AND token = 'm28tbNLsYcW++zKfQq2U+SqKErVYooDK76TUsVv4ft4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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