SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e675e9208b7a50beff91346d535ee47a718491f176fc4e94c656bb1ff5735eec' 
  AND token = 'zwJKrItsym9349Yt+7Um6pVrq1xosXS+aAVnbbWZzUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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