SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '242d304eef04562797f2d5a99c89ae7b28615d2472d6c03a3ae9b434c8d594c6' 
  AND token = '2rFa+DZxZZ3x/JVqOIjZwjaMvRtzv7IAuzmtriapgUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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