SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20b8cd0cb7b8ece7ac85e74b793c2a7e555d4841af9cf4d41f1d08895e562d9d' 
  AND token = 'KLIThCLsTOWrv5V4ptZKY8Wpa/6LsFOsNSpQZqmAlvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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