SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2632ff5271df9e3adeb5bdcb5c764a9da275f711541414fa4a5fb3f8d323c12' 
  AND token = '43vwAtdKWqtUwXMs92uY88n+tW+yra7XsUugwB86oZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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