SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28009ba0b5537e34ee3883e7674a49224502e6b4ca522aa3fba144c8f483fe78' 
  AND token = 'PR2kU8MkeFWhzHtMdWbvBzJHQgBxpaBYRdrWB3NupQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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