SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '871ae7b7c821402492d18760c28d38518f466115245f4d0a94372589b066b982' 
  AND token = '3fbABdzQvPIzVNME4YZGyHy418hwLvtsuPl4L3GDYx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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