SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7f4e9e2d805141460ce2ee600146c5a16e42b8b155925381bb5d477bca59482' 
  AND token = '6ZjQ8IFfWuHLmXoKY9FvEOqGm/cPpaKxnc8KIRzNSwc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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