SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd67813f508107083205fecf04b3250efd09923edfd25c21985935a265b719263' 
  AND token = '4AAWHtzfUbFaqM6R9jmrXnPWHZjoXNXd24Ss7OmfV4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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