SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2135bbfdd8997d7e590aac048d5dd9d18044f08556a116a8b2aea8ef51208fb2' 
  AND token = '3OJz5F+VhNcOW9MLpSoGXOlrZWLNOM2cWl5tMW046q8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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