SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd42875fd1f344a5fa7083747ac561053db1cdb600e4d7f9de181473099913061' 
  AND token = '29hbh/xjQplnIv42vOKU3cqfXPyJpIQkTE9Ypw/JFqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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