SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a976111ed8ede143079adab3a76161d07c81dd7af7d096484d2d818a60c40e8f' 
  AND token = 'Z9+nkUjMMm/XmysyLRmZjL8hijWDxxAj10QwPxho+90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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