SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd50879dc9fe851d365daad6bae700e3b42866e21509d0fbaf0f824ffb6d36b28' 
  AND token = 'YY2ylxKTpR/0UxR0C6aYefmVG2/5kOey0ShuUpU4ZcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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