SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e9343885ea41a32bc160d1d2f5e1b8517b7d8a4655075ae5be0d37a087d6606' 
  AND token = 'a7/uJBLshIew2+xf65eemKTvHsLU/FuE3pDntNGoO50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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