SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d5028fea11e467074d79c93803da3da871583546917ff1b839171ba695504b2' 
  AND token = 'Iol9AxUrQ5pEK6fT0KvcFNRcn+8JFfuRFtaOR4vVDN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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